i feel it is best to buy a dmd fully working for your first pin. best bang for ya buck.
(buy a working machine, because if u get bogged down fixing something, it might put you off buying more pins in the future).
a great dmd machine can be had for around 2 grand. Oscar should still have some great titles left for around that money.
It all depends where you live. plenty of great machines available for around 2 grand.