You could have a look at the atarihacks ...maybe there is a ram project there.. http://atarihacks.cjb.net/
You'll need to be able to use a soldering iron/ or have large testicles of course.
I agree the prices at some atari sellers are more than a bit crazy... 25 quid for a 8MHz 68k chip is nuts and a lot more for the customs... better to get an old machine at a market/ebay for spares. It also makes me wonder when I see they advertise for Jinnee+NVDI+magiC combination.. Given the cost I wonder if many old atari users actually do..
I'm still using tos2.06 on a STE... and I want better video.. I have an old ET4000 ISA card.. has anyone tried this project? what will it give me? better resolutions? more colors? or just the same STE resolutions on a VGA monitor?