This is pure speculation, but I think Elwins pins are going to be the most saught after pins as they age into the market. They just shoot SOO fucking well. It's hard for me to admit it as I'm not a huge stern fan, but his designs are the best ever IMHO. I've probably played at least 80%+ of all modern pins, and his games are insanely good by comparison. You can tell that he designs as a pinhead, not a "designer." GOAT.
Random dude of the net recommendation: Buy and hold.