I had a similar experience consigning there a long time ago. I sent him a few modern posters, not very expensive but relatively expensive for modern. After he received them, he suggested to list them in eBay auction, so I said OK. One poster that I remember is a Death Proof quad (great poster, sold for about $100) and a few others for $50-$130 - about average market price, and the commission was 50%.
I had a similar feeling about emails, also. About 2 months after the sales, I messaged him for the payment and he sent it. Not a great consigning experience, but at the time I had recently paid about 10 times more than market price on a handful of common posters from Cinemasterpieces - clearly I was a newbie to buying and selling. In the long run, those deals compelled me to do a little homework, and essentially paid for themselves haha.