[DonRotolo]

Used tools are OK, and can often get you much more machine for your money.
Search ChiefDelphi for many, many mill recommendations. I remember Dave Lavery offering a particularly good choice.

Far more important than the quality of the machine is the quality of the operator. An excellent operator can turn out world-class items from a poor machine, and a poor operator* can fail to turn out usable items from the finest machine on the planet.

Many schools / teams decide that CNC is the way to go, as a way of compensating for their inability to actually operate a milling machine. They let the computer make the decisions, and the result is just fine. I am of the opinion that having one or two kids on the team become excellent operators is a far better method.

So, find a local machinist or three, and see if you can get them to teach someone - ideally a Sophomore (who will be with the team a while) how to use a manual mill. And/or maybe introduce you to someone in the used machinery business who can find a nice machine with tooling (which costs as much as the machine!) that's within your budget.

My 2 cents.

*=almost any high school student who hasn't been taught.