Im not sure about bristlenoses, but livebearer fry in general go for pennys at most unless they are unusual or rare or pure bred specimens- i would ask though at your lfs wether they take fry off people at all firstly because some don't due to insurance reasons.
Well if they are in a fry tank, put them in the main tank with the adult fish and they may eat some if they are still smaller enough. Otherwise there's a buy/sell section on the forum or you could just find another lfs that will take them.