Stop over at NewEgg for most of the stuff- Case&PS (~50), mobo (~80), 32 meg GF2 (30), 30 gig 7200 rpm HD (54), 52x CD (22), and a 1700+ (42). I know it's not exactly a 1.8 ghtz, but it's a good chip with great OCability. Crucial PC2100 is 47.
Go to NexFan for your heatsink (ND-18 for 10), 80mm fans (~5), and the floppy drive (8).
This doesn't include a keyboard, mouse, monitor, or operating system. The LCDs are what's going to kill your budget, but it sounds like you know that.
I was just put in charge of putting together about 20 PCs for my business and this is what I've come up with for the best balance between cost and performance while not sacrificing quality. ($42 for a 1700+ is unbelievable! I paid $179 for my K6-2 350 not that many years ago.

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