[rm -rf /]

If you're stuck for space and/or cash, you might consider a combo mill/lathe/drill. It won't do any of these tasks as well as the individual tools might, and it's small (but so, relatively, are the robots), but it wouldn't take up too much space and would at least provide you these capabilities at a lower cost than the individual machines.

I think that there are other teams who use one of these as (one of?) their primary machine.

A quick google search ("combo lathe mill") will show you a number. From what I've read, there's basically a price/quality relationship. The more you pay the better the tool, so, if you go this route, buy the best you can afford.