A Taig for 1730 +shipping from DeepGroove1 on Ebay is about the minimum machine I would use for aluminum. It actually does ok if you bear in mind its limited horsepower on steel and cast iron as well. You could actually make it with slightly bigger steppers and the same electronics as Paul's for a couple dollars less, but his is basically assemble and go. No Paul isn't my favorite person on the planet (he hasn't treated me bad, but some have heartburn over his past offerings), but his current offering is quite decent. (He actually gave me some decent after the sale service and information.)

Just add computer and Mach3.

I get a certain amount of production work out of mine, although mine is also highly modified.

Sorry to any Proxxon fans, but I have never seen one up close.

The next more rigid machine is probably an Emco F1 for a lot more money.

The next close machine is probably the MaxNC now made by XiMotion. I have one, and while it does have antibacklash nuts the Taig doesn't have its not as rigid, and it has rigid couplers. Unless XiMotion has made some changes, the screws are just supported by the nuts and the motors. The MaxNC 5 is substantially smaller and a little cheaper. The 15CL has some advantages, but it costs more.

If you want more envelope, but at the sacrifice of rigidity a plastic or MDF gantry style router might be ok.

I do not think of Taig as more than a hobby mill, but it really is probably the best bang for your buck in an almost ready to go CNC mill.