Very interesting and gives me something to think about when the day finally comes to sell my art.
Not all of the paintings we do are worthy of being matted. But after a period of time, we do know which are our best. A good rule might be: if I would hang it in my house, somebody else might like to too. So it should be finished. It should be protected. And it's easier on the budget if you buy the mat when a painting keeps coming back into your head as having merit.
A single flap-mat shipped to my house from Frames By Mail retails for: $26.77. A double flap-mat shipped from the same source costs: $29.04. For the difference of $2.27, I would be a sport and double mat. (Once the decision has been made to be in the art business, and sales are booming, of course, a new source for matting would have to be found. With a business that's got cash flow, I would be interested in buying cut flap-mats wholesale, since multiples would be required).
Going into the art business opens up a can of worms. A lot of thought has to be given it aside from "Gee, I should sell my stuff." Or the comment we get from friends, "You're really good. You know what you should do? You should sell your stuff." The idea is great. It's flattering. But implementing it is something else: a lot of research and a lot of work.
Dan, you can't start too early if selling online or out of a gallery is ever going to be something you want to pursue. You have to poke it around while you're painting. From this poking, I'm thinking I'll mat the paintings I've shown you here over the next few months, (I did think about them while writing this post), but here's a thought: maybe working on canvas is preferable to working on paper? Storage is easy and nothing needs be added to make the painting presentable.