some places carry all sizes, with the smallest being dime sized, and the prices start at around $5, and can climb to over $25 dollars for a regular 4" fish.
the specimines with better, longer fins usually sell for more. for example, a quarter sized angel with short fins that havent grown out yet will go for about 8 dollars by me, while the same sized angel with fins that have grown out go for over $12. as i said, a regular 4" angel with regular fins goes for about $25, but if he had long, grown out fins or he was a veil, he could easily command $30- $40