So many good games out there that can still be had for under $3500....but most of those are going to be pretty simple by today's standards....not necessarily a bad thing. Those with more complicated rulesets or really cool toys/gimmicks, tend to fetch a premium that pushes you above that threshold. The exceptions tend to be games that, frankly, are price restricted by bad art/translites or niche themes. Give those a serious look if you want to stick within your range.
Good examples, within your price range, all day every day.:
BSD:. Dark and moody. Excellent theme integration.
Great gimmick (Mist), 3 different multiballs. Scares the sh&$ out of little kids.
Shadow:. Sanctum lock is cool....but tough to find a machine without Sanctum wear. Ability to divert balls on ramps on the fly. Upper playfield. Translite sucks but has the best alternate translite/art package ever made, which can easily be had.
Dr Who: Cool motorized mini playfield. Good topper. Ability to choose a doctor to play as, each with different advantages. Looks really good with LED conversion.
Johnny Mnemonic:. Plays fast. One of the all time best wizard modes (Powerdown). Midnight madness. The glove and matrix ball lock is a cool feature. Art package totally sucks.
Ripley's believe it or not:. Probably on the border of your price range. But super complicated/deep rulesets and that machine has everything but the kitchen sink in it.