I sell my framed canvases at around 6x cost of production as calculated in a realistic, beady-eyed way that would make any bean-counter proud. Gives me 5x profit on direct sales, or 2x profit from gallery sales, which is above average for most artists.
The market for large canvases includes the enormous demographic of people with large wall spaces to cover. The nice thing about those folks is that they can rationalize the purchase of large art from a pragmatic, home-improvement or reception-room-statement point of view. That market is many, many times larger than the market of people such as collectors and aficiandos who buy art for its own sake. I have no qualms about that at all. My clients are thrilled to have the pieces, and I'm thrilled to have an art product that allows me to make a living from photography during recessionary times.
Does that include your time for making images? Just curious how far you drill down on this. I used to try and calculate that and as a commercial photographer too I know what my shooting time is worth. But I realize that on some images while I may make some sales it may be years before I actually cover my shooting efforts. An example is Shiprock. I have made numerous trips there over many years and have yet to get my "definitive" image. When I do get it I should really calculate in all the costs of the failed attempts. I sell 8x10 inkjets for $400 matted and sales are brisk this year (2012 second best year I have ever had). But at that price (if and when) it would take some time to recover all my costs pursuing some difficult images.