I might suggest you look at your local free ads. This week I just picked up:
A12oo, 8meg Fast Ram, 800Meg Hard drive, joysticks, mouse, 40 originals and a 1.3 A500 1meg...... £40 the lot!
Go back a couple of years and I picked up a monster A12oo 68o6o Tower system for £150....
Bargains are out there... don't just be relying on Ebay!