If you bought an A1200 you surely know already what it can and it can't do, what I guess is if you've correctly evaluated how much you would spend on a computer that - after all - will just be your "nice toy" for spare time. Providing you won't do on that much more than you did - or you could do - 15-20 years ago, it's only matter to spend money to add rare hardware for the curiosity to see it running. Here you will find many people ready to suggest rare, costy and barely-findable technology gadgets that in the outside world don't worth a cup of coffee, and also some people like me, who will friendly try to demotivate you (you know, money are difficult to earn...).
It doesn't have to be monster expensive though there are some expenses involved.
Hard drive, CF transfer kit, a pair of PC speakers and an adapter cord, external scan doubler, and a cheapie accelerator, you can sneak for under 400 bucks.
I'd stay away from the crazy powerPC cards and whatnot, where you are going to be shelling out over 500 dollars likely for very little real benefit.
edit: For my setup, the biggest cost has honestly been peripherals like speakers and an LCD monitor to use with it (Since I can't fit a CRT at my desk)
