In the past year I've had 4 machines.
BF - bought off an OP. Sat on CL for a couple weeks. Negotiated them down to 2200 due to burn in on the display.
JP - 1150 from a local collector. Total project aka only had GI on power on. DMD was known to be good.
PM - Messaged by a collector on here out of the blue because it was in my wishlist.
RBION - Held my BF for trade. Caught a lot of flack, but ended up with a straight off route rbion and 150 in cash.
That is just me. I have friends who have gone through many more machines in the last year. You have to have the money on hand. Know the collectors in your area. Be prepared to drive. Be flexible in what titles you will take. Once you have something desirable, leverage it to get exactly what you want. Oh, and be prepared to get a lot of time wasters. Only thing holding me back from buying more machines are funds.