It used to be that good configurations for Unix were what the market called ‘server’ machines, with beefed-up I/O subsystems and fast buses. No longer; today's ‘servers’ are monster boxes with multiple power supplies and processors, gigabytes of memory, and industrial-grade air cooling —they're not really suitable as personal machines. A typical SCSI desktop workstation is as much as you'll need.
Prices keep dropping, so there's a temptation to wait forever to buy. A good way to cope with this is to configure your system on paper, get a couple of initial estimates, then set a trigger price, below the lowest one, at what you're willing to pay. Then watch and wait. When the configuration cost hits your trigger price, place your order.
The advantage of this method is that it requires you to settle in your mind, well in advance, what you're willing to pay for what you're getting. That way, you'll buy at the earliest time you should, and won't stress too much out afterwards as it depreciates.
Before you shop, do your homework. Publications like "Computer Shopper" (and their web site at http://www.computershopper.com) are invaluable for helping you get a feel for prices and what clonemakers are doing. Another excellent site is ComputerESP.
The most important where-to-buy advice is negative. Do not go to a traditional, business-oriented storefront dealership. Their overheads are high. So are their prices.
Especially, run —do not walk —away from any outfit that trumpets ‘business solutions’. This is marketing code for the kind of place that will justify a heavy price premium by promising after-sale service and training which, nine times out of ten, will turn out to be nonexistent or incompetent. Sure, they'll give you plush carpeting and a firm handshake from a guy with too many teeth and an expensive watch —but did you really want to pay for that?
There are two major alternatives to storefront dealerships and one minor one. The major ones are mail order and computer superstores. The minor one is computer fairs.
I used to be a big fan of hole-in-the-wall stores run by immigrants from the other side of the International Date Line, but most of those places have been driven out of the regular retail game by the superstores and the Web. If you still have one in your neighborhood, you're lucky. I do, as it happens, but that is now unusual; the only place you normally find diaspora Chinese and Indians selling cheap PCs over the counter anymore is at computer fairs. (Usually they're doing it to publicize an Internet/mail-order business.)
You can find good loss-leader deals on individual parts at these fairs (they're especially good places to buy disk drives cheap). But I call them a minor alternative because it's hard to get a custom configuration tuned for Unix built for you at a fair. So you end up, effectively, back in the mail-order or Web channel.
Internet buying makes a lot of sense today for anyone with more technical savvy than J. Random Luser in a suit. Even from no-name vendors, parts and system quality tend to be high and consistent, so conventional dealerships don't really have much more to offer than a warm fuzzy feeling. Furthermore, competition has become so intense that even Internet/mail-order vendors today have to offer not just lower prices than ever before but warranty and support policies of a depth that would have seemed incredible a few years back. For example, many bundle a year of on-site hardware support with their medium- and high-end "business" configurations for a very low premium over the bare hardware.
Note, however, that assembling a system yourself out of parts is not likely to save you money over dealing with the Internet/mail-order systems houses. You can't buy parts at the volume they do; the discounts they command are bigger than the premiums reflected in their prices. The lack of any system warranty or support can also be a problem even if you're expert enough to do the integration yourself — because you also assume all the risk of defective parts and integration problems.
Watch out for dealers (Spectrum Trading for one) who charge ridiculous shipping fees. One of our spies reports he bought a hotswappable hard disc drive tray that weighed about 3 lbs. and cost $250 and they charged $25 to ship it UPS groud.
Don't forget that (most places) you can avoid sales tax by buying from an out-of-state outfit, and save yourself 6-8% depending on where you live. If you live near a state line, buying from a local outfit you can often win, quite legally, by having the stuff shipped to a friend or relative just over it. Best of all is a buddy with a state-registered dealer number; these aren't very hard to get and confer not just exemption from sales tax but (often) whopping discounts from the vendors. Hand him a dollar afterwards to make it legal.
(Note: I have been advised that you shouldn't try the latter tactic in Florida —they are notoriously tough on "resale license" holders).
(Note II: The Supreme Court has ruled that states may not tax out-of-state businesses under existing law, but left the way open for Congress to pass enabling legislation. Let's hope the mail-order industry has good lobbyists.)
Big chain superstores like CompUSA give you a reasonable alternative to the Web. And there are good reasons to explore it — these stores buy and sell at volumes that allow them to offer prices not far above the Web. (They make back a lot of their margin on computer games and small accessories like mouse pads, cables, and floppy disks.)
Note, however: Avoid Best Buy. Horror stories about them are legion — predatory salescritters, incompetent service, routine bait-and-switch tactics.
One thing you should not buy remotely if you can avoid it is a monitor. Monitors are subject to significant quality variations even within the same make and model. Flatscreens haver this [roblem less than CRTs did, but you don't want a flatscreen with dead pixels. So buy your monitor face-to-face, picking the best out of three or four.
Another good argument for buying at a superstore is that you may have to pay return postage if you ship a system back to the vendor. On a big, heavy system, this can eat your initial price savings.
The only major problem with superstores is that the salespeople who staff them aren't very bright or very clueful (it's a sort of Darwinian reverse-selection effect; these are the guys who are fascinated by computer technology but not smart enough to be techies). Most of them don't know from Linux and are likely to push things like two-button mice that you can't use. Use caution and check your system manifest.
But if you shop carefully and don't fall for one of their name-brand "prestige" systems, you can get prices comparable to Internet/mail-order with the comfort of knowing there's a trouble desk you can drive back to in a pinch. (Also, you can see your monitor before you buy!)
You can often get out of paying tax just by paying cash, especially at computer shows. You can always say you're going to ship the equipment out of the state.
A lot of vendors bundle Windows and variable amounts of apps with their hardware. If you tell them to lose all this useless cruft they may shave $50 or $100 off the system price.