I'm new to this hobby/collector thing myself. My interest in WW bought me to this site as I now have the means to afford a couple of machines.

Based on my own very limited experience, so called B-list games are where it's at. They represent the biggest bang for your buck IMO and after I started seeing some crazy prices for even B-list WPC/Bally games, I started looking towards DE/Sega, Capcom, and Gottleib. All the sub $2K prices for DMD WPC/Bally are over in my area it appears unless it's in really rough shape. While they may certainly be the cat's tits, as someone who only has so much disposable income for another hobby (I build and fly RC planes and helis), I feel as though I'd rather have 2 games by someone else than just one by Williams. I've talked to a few others and they feel the same.

Bubble? Probably not, more just cyclical of people entering/leaving the hobby. I will say, if Stern and JJP and the others keep raising their prices to that of small cars, they can kiss their collective arses goodbye long term. There are tons more things I could drop $7K+ on than a game that gets played at most, a few plays a day. Hobbies ain't cheap, but that doesn't mean they have to be ridiculous as well.

These are just my opinions of course.