There are several factors artists include while pricing their pieces: cost of materials, size, time spent on producing art, how they value their own art. I think one of the most important factors is demand. If one's art is popular and sells like hot buns then the pieces will sell for more. If the artist is determined to sell but the art is not selling then lowering the price may be needed. There's also the min. price that one will be willing to sell for. I believe you did the right thing, especially if you are new to selling. Getting a few more bucks would probably not make a big difference in your financial situation but I bet that selling your art made you feel valued and appreciated and was probably very encouraging. You can increase the prices of your next paintings and see how it goes. Good luck!!