Calling me 'bro' tends to raise my suspicious. I have sold and swapped a lot of cards to people who contacted me, but I always ask them to send to me first. I have a good reputation and they could call me out if I cheated them. There is the option of putting cards on the market for them to buy, but there are fees and someone could snipe them if it's a low price. Selling cards in bulk is extra hassle.
I see he responded. He needs to send the rest of what he owes you.