Nice idea for a take on this theme. The text was positioned right over a black line in the background, making it more difficult to read. Moving the text up or giving it it's own background would help a lot. I also quickly broke the bartering mechanic when I realized I could offer 1 gold to make them keep going down until they hit their low, then offer the low. This resulted in the last few offers always asking for 105 and never more or less. Good framework though!
Lovely art. Did you handpaint these then scan them in?