First rule - don;t buy something you haven;t played. I don;t care if you play it on the Wii, xbox360, pinmame or search them out locally at bars to play. Don't ever buy a pin solely based on the fact it fits your price range or because someone tells you it's good. Buy it because you KNOW YOU LIKE it.
Second rule is to not over pay. I'm amazed how many people buy their first pin and have over paid and when times comes to sell it you have a miserable time getting rid of it. The reality is your first pin will most likely be the first sold. Visit sites like pinpedia.com or bostonpinball.biz
Third rule - do your research (download the manual) and know how to get into the diag menu. Make sure you either do it or ask the seller to do it. If there are issues this allows you some bargaining power.
Fourth rule - research common failure items and know how much it'll cost you to replace it such as a display, CPU or driver board. When looking at a pin remove the traslite and inspect molex connectors (burned or not) and LOOK HARD at the battery holder. If it's a battery leak victim and the acid made it to the PCB, you can safely assume an expensive fix is due.
Pinball is an expensive hobby. Most people start off expecting to pay $800 - $1200. BTW you didn't mention of you wanted an EM or a SS. An EM be had fairly cheap while SS's typically run much more (depending upon title of course).
Price doesn't mean a GREAT machine. Lindsey pointed out a MM and those are one of the most expensive. While I personally like the game, I know several people who think the game sucks. Back to more money doesn;t always mean more fun.
The bottom line is YOU need to FIND what YOU like. There's soooo many titles out there and thank god for that.
It has been my observance that there is
typically two types of groups. Stop and go OR flow.
Let me explain. Using commonly liked titles - LOTR and AFM. I find that the people who dislike LOTR like AFM and vice versa. Why? Because those people want a fast paced game with FLOW and LOTR is more stop and go. All my pins are Stop and go titles.
For me personally, I KNOW what my "IT" factor is. With more time on different titles you'll eventually figure out what your "IT" factor is too.
It's not to late to walk away and save yourself from this disease.
