I agree, flat not glossy. Your cutting looks great. I always use a rigid backer. Just my personal preference. As far as pricing, I double the cost of my materials and then add a per hour amount. I usually do $10.00 per hour it took me to cut it. If my wood, frame etc cost me $10.00 and it took me 3 hours to complete the project, my price would be $40.00. It also depends who I am selling to. Friends usually pay less, I stand fast with my pricing at a show and galleries usually charge way more than I do, but that is usually a commissioned sale by percentage. Never apologize for your price.