My opinion is that is has the potential to be more profitable than a larger painting, I am not a painter but I make copper sculptures, my larger sculptures take a lot of time to make, the materials are very expensive since copper is at $4.00 a lbs. , the brazing rods I use have 15% silver and cost over $160. for 1lb box and 1 large sculpture will eat it right up. So if the work is interesting going small has a big advantage, shipping cost, ease of handling the smaller items, displaying them. So I think your on to something. Now Like I said I'm not a painter but I did make 1 small mini painting but it's actually a sculpture and not a painting, confused? here is the image which will clarify what I'm talking about, this small painting sold for 10 times more than a larger one would have sold!