I dunno if you would call it easy, but the Midway door I'm restoring has actually been completed disassembled, stripped/de-rusted, and repainted.. even had to hammer out a couple of spots.. and it's looking great..
If you get a Coin Controls or Happ coin door it will be even easier since you can replace almost every part as long as the frame is good. Just look out for items that appear mechanically complete (although most parts can be replaced, keep in mind).
And if you buy a rusty one, just get one of those paint/rust stripping wheels for a drill.. works like a charm and leaves a nice, bare, somewhat scratchy surface for priming.
If I do a 4P coin door on my next cabinet, I may just buy the door, a bucket, and fashion some sort of holder myself to save over an over/under combo (saves a little, anyways).
Also, you might want to try videoconnect.com.. call them for a price, but they're always cutting deals on nice stuff like shifters, pedals, 4P coin doors, and even analog sticks.