I learned to be tough about my pricing from my mom who did the craft fair scene for years (she made personalized christmas socks - all quilted and appliqued), baby stuff (like bibs and towels and whatnot) and all kinds of really beautiful knick-knacks. She always said that you should charge what you think it is worth PLUS 20%.
she was always really awesome to her customers but would politely take NO CRAP from people who said they could get "the same thing" for less.
Also, my boyfriend is a webpage designer. He has been instructed (after being far too generous a few times) that he should charge what he thinks he deserves TIMES THREE!
never sell yourself short.