It’s interesting you cap it at 16, I think that’s exactly how many I got. Mostly $0 for PWYW, but a few were presented well enough to warrant a purchase.
More than anything it’s curiosity. I’m going to be submitting some material there and I wanted to see what the market was like. Overall I can say I’m surprised that the stuff I got was better, on average, than I expected. Some have really crappy layout, and do come off as someone's house rule document saved as a PDF. You can pretty much tell a product isn’t worth it when the entire tag line is something like “This book has new feats”.
So, one book of feats, one book of archetypes, and the rest are all Monster & NPC books, which as DM I have the most use for and save me the most time.