I have housed my a1200 in a Compaq deskpro, they are a faily large desktop are very in expensive, I have had to make some mods and a new backplate but achived this for £15 inside i have mediator sx, hard drives, cd rom etc via ide express and also with a slot cut in the side i can still use my pcmcia card.
i do agree you will have a problem with power if you do not have an alternative source.