I’m pretty new at this yet. I’ve only been collecting since the fall. I purchased a lot of large lots through Craigslist (I put a want ad up), local antique and resale store, and now I purchase mostly on eBay. I scored most of my rare ones on eBay due to poor photos by the sellers. Sometimes you just get lucky. As I see more marbles, I get a better idea of which are the more common/less collectible ones. It’s taken me awhile to figure this out though. Now of course my eyes are gravitating towards the more spendy ones. 🤣