250 is a good price, if you want a pair get them from patrick at
http://www.saurian.net he has great frogs, and excellent service. I got a pair of surinam cobalts from him and I couldnt be any happier with them, I expect them to breed any time now. I am also on waiting lists for about 15 frogs of diferent morphs and species. He has multile bloodlines so you can get a unrelated pair. With dart frogs you can go up to f10 without problems, but I dont feel comfortable with going past f3-f4.