I like COMC. Been using it for years. Mainly used it for the US mailbox service and saved a lot in shipping many purchases from USA to Canada. One thing to note when getting stuff shipped from COMC to you, since the warehouses are in the US, you’ll likely pay customs fees. Some people don’t realize this and it can be a surprise. On the other hand, you don’t pay monthly storage fees for them to hold your cards. You only pay the processing for them to receive your package and upload the cards to your account.
I had a small amount of cards listed but for a while and would get the occasional sale, and I did some flipping. Eventually I sent more in (I’ve always submitted directly to COMC at the expo in Toronto) and have loved the convenience of them handling the shipping, and just avoiding some of the BS the occasional buyers bring on eBay. From my sales probably about 30% have come via eBay on COMC since they list many fixed priced listenings on eBay anyway.
I don’t get the volume of sales like I did during the pandemic, but to be fair, while the market has slowed since then, I also don’t have a lot of new product and current rookies listed either. I am a patient though, which I think is important.
A few tips for selling: cards listed for $0.75 or less don’t incur monthly storage fees. However, this was better when it was $0.30 per card to submit, whereas I believe it’s $0.50 per card now. For cards in the $100 range, if you list at $99.74 or less, you don’t pay the elite processing. Before sending stuff in, search your cards on COMC to see what others have them listed for. Once sets hit UD epack, people can transfer their cards to COMC, which floods the market fast and asking prices can plummet. Finally, if any of your cards have creases, chips, rough edges, etc, its often best to keep it. These will often get a condition note or sometimes rejected.