Congratulations! The thrill of selling never wears off. Price is dictated more by name than artwork. That's the game--build a name. I've seen artwork similar to yours command ten times what you sold for. The more your name gets known, the more you sell, the higher you can raise your price. Usually. An art gallery generally won't represent an artist who cannot get $1 per square inch per painting. 12 x 16 is 192 square inches which would be $192 at the lowest end for professional artists, to give you an idea of what to aim for. But nothing is set in stone. You get what a purchaser will pay, or what you feel is fair for you (time and work put into the painting) and negotiation should not be ruled out. Building an art career takes years. Let your first sale spur you on to many more. And good luck!
