For those of y'all doing this more as a hobby (like me), the Whatnot app seems to be a good tool. It's kind of like a live eBay. My wife has a store from which she sells Disney and Harry Potter stuff. With shipping, which is usually a couple of bucks, one will sometimes hit on something that can be found a tad cheaper on normal venues; however, there are a couple of advantages. First, it is an auction, so you don't have to pay more than what you think it's worth. Secondly, the hosts have giveaways throughout the show. You don't have to buy anything to enter a giveaway. The rooms I peruse usually have less than 100 people, so the odds aren't bad. Thus far I've purchased 3, 1-oz silver coins for $96 (includes shipping). This is close to what it would cost at JM Bullion, assuming you're not buying in bulk.
Lol. After rereading, it sounds like I'm trying to sell some scam. I promise it's legit.