We went with a CNC Jr from CNC Masters (
www.cncmasters.com). The control software is a bit buggy and irritating, but now we've played with enough to figure out how to best use it. The whole setup is less than $10k, so you get what you pay for. They're located in SoCal, which is nice and they've been very helpful by phone with any of my needs and questions. Last year, during build season, we blew out a control board when the power to our building went out (yes while the CNC was running). I packed up the control board and sent it to them on a Thursday and had it back the following Wed. Not bad service!!
We've become better with MasterCAM, which is a really cool tool that can speed up and expand your capabilities on a CNC - so don't forget to add on a license or two for that. I think you can get a edu version for about $1k.
There is also microkinetics which has some really cheap CNC offerings. I have one of their desktop mills which will do a lot, but it will do nothing fast and nothing that big. I've made transmission plates on them, but you have to do 5-6 passes for 1/4" aluminum - YAWN!!
Good Luck.