If you reload the 500 using hardcast bullets, the cost comes way down.
50 Caliber: about 50 cents each.
Or cast your own for about 3-4 cents each.
WTB HP22 and Taurus 94ss (San Jose, Sacramento): Link
WTS Mosin Spam cans Romanian 7.62x54R and also 7.62x39 7n6 in NorCal: Link