Depends on who you sell it to. If you sell it to someone who can take care of it for its whole life. then easily $30. I have no problem taking a cut on price to see that a fish goes to a good home. If you are gonna sell it to jsut anyone then i've seen 7" go for as much as $60. I like keeping the price high on fish like this and redtail cats and such. Yes its inconvenient for those that want them, but also weeds out those who think they are just cute and impulse buy. Cause thats a good chunk of change right there,.
Sorry to derail on you. 30 for experienced fish keeper and 50+ for everyone else.