Also look for older Haas MiniMills; these came out in 2001. We have one dating from back then that has done many thousands of hours work with minimal maintenance.
I think the advice to consider getting your parts done outside is probably the best. Unless you are an experienced machinist it is a big challenge to design, prototype and then produce parts on your own machine; much better to farm it out to experienced people. Be upfront with anyone you deal with, explain your long term goal is to do your own in-house manufacturing and be willing to pay a sensible price for what you have done.
An open mind is a virtue...so long as all the common sense has not leaked out.