Pricing of Art. Should the Price Reflect the Time Spent?

I am about to submit some paintings to a gallery, and as always that dreaded conundrum of how much to charge for my precious works of art comes up.

Mary Kemp. Work in progress.
(This picture hass nothing to do with the paintings I'm talking about but simply what I'm working on at the moment!)

Two are roughly the same size. One is quite simple and didn't take too long to paint, but the other is much more complicated and took ages to complete. I've framed the complicated one more elaborately so that in itself gives it a bit of extra value, but I'm still not sure about the price difference. But of course you could say that each painting is the sum of your training and experimentation over the years so how long a painting takes brush to canvas is irrelevant to the price.