Generally I'd say find an 030 and put some ram on it rather than just get a ram card. Fast ram alone will just about double the speed of certain operations on your 1200, but an 030 card makes your 1200 a much more useful machine, as I'm sure you know. Trouble is they seem to be a bit more expensive on Ebay these days.
Having said that I would ram cards are quite rare.
.... and If you do get another 030 you will be able to have evenly matched games of Doom and AB3D: TKG etc using a serial link-up.
P.S.
PowerMonger link up rocks.
