Hello charlie, products are ,by default, priced at the markup of 50% over wholesale cost for full-priced orders. Your profit on product order is 70% of profit on the sale (defined as total order amount less wholesale cost of the canvas, tax and shipping).
As an example, lets say wholesale price of a 30x30 canvas is $100,00. If the photographer has a markup of 50% then we will sell that photo for $150,00 (i.e. 50% more than $100). The photographer will get 70% of the net profit which is calculated by taking the retail price less the wholesale price (i.e. $150,00 - $100 or $50.00). So in this case the commission would be $35. If the photographer chooses a 1000% markup then the canvas will sell for $1000.00 and the commission will be $630.00.