@irishmike:
Keep in mind that Mediator or no Mediator, with only an 030 cpu any kind of higher res display (through AGA or through Voodoo 3) or any other major system expansion for that matter will feel sluggish. You need an 040@40Mhz or 060 accelerator card, ideally, and then work your way up on adding stuff like graphics cards, etc.
If you prefer the original Amiga casing, then your only option is to go the A2000/A3000/A4000 route, or get a BlizzardPPC and BVision and use them in the desktop case (extremely hacky and requires extra, extra, extra cooling).
Either way, it's going to cost a lot I'm afraid. :-(