I am sure they take credit cards. I imagine they will have their ipads with the credit card attachment just like they do at the gallery and sales at the theatres.
It has to do with the artist and the number of colors. More colors is more work which equals a higher price. Add in Struzan and you get the higher than normal price.
I absolutely loved the way this episode ended. You went from what happened to Lane to Don taking Glen back to school and letting him drive the car. It was just great.