http://namlhunt.homestead.com/MLpowders.html

This is a 5 part comparison of 777, BH 209, and Black Mag XP. Part three discusses cost. For a 110 gr load, BH costs 53.5 cents/shot and Black Mag costs 77.5 cents/shot. Black Mag would have to be REALLY better to command that price especially since it is so hard to get ahold of.

The articles make for some interesting reading. Also pretty obviously slanted toward BH 209, it does give some great info.