I have monkeyed with TCGplayer Direct for a few days and I think it has a few very distinct advantages over both in-person buylisting that doesn’t let you sell cheap cards or large quantities, and online buylist aggregates which all come with their own set of challenges. ...
but this may be the best service for that if you're in that position. Also, if you're selling cards through eBay or tcgplayer...you still have to pay them out, sit on product until it sells, deal with more instances of shipping, and of course spend much more time dealing with these...