Got it working
I got a 2012 mac mini (2.3ghz quad core i7, hd4000 model) working with a Vidock (external graphics card enclosure). So long as you have Windows on it (took so long to get it bootcamped) setting up the actual e-gpu took me about 10 minutes. The gpu inside my vidock is a gtx 560. Plays games such as Battlefield 3 and DayZ great (the CPU in the mac mini doesn't even break a sweat, its crazy).
I got a 3dmark06 score of 18431. The same e-gpu I previously had with my 2011 dual core i5 macbook pro netted a score of 14273. A very nice boost and is even more noticeable while playing games. So far no one has gotten a TB e-gpu to work under os x, so you'd have to have Windows 7 or 8. But given the mac mini I bought came with a stock 1tb hard drive, there's more than enough space for a second partition (and four usb 3 ports).
Oh and I connected my Vidock to the mac mini via the sonnet echo thunderbolt/expresscard adapter.
Edit:
And price wise, you could get the vidock+sonnet adapter for as little as $350. Add 800 for the mini, 100 for a screen, 150 for a solid gpu, and this desktop beast still costs lower than any gaming laptop but with way more power.