It really does depend on your budget and what sort of condition pin you are looking for.
Most pinball machines from a dealer have been fully shopped, with many man-hours going in to cleaning the playfield, plastics and posts, replacing all the rubbers, fixing up any problems with coils, boards, displays and so on. Obviously they have to pay their staff, so you will pay a premium to a dealer.
If you are lower in dollars than you will need to look at pin where you can do some or all of that work yourself. You may still have to pay for spare parts so keep that in mind - ideally you want something that is mostly working and where the playfield is not too beat up.
As pinballist said, you may be better off going for an earlier solid state machine on the cheap for now, do it up and sell it off - if you do that two or three times you will probably find that you can then afford one of the titles you are more interested in.
