you can buy PRVI ammo and keep the brass, or buy PRVI brass from trade ex. These are boxer primed, so i use CCI 200 as the primer. I have kept GP11 brass but have not gone through the trouble of decapping them (berdan is a pain in the ass). Canada Ammo has brilliantly starting offering dominion brand (house brand) berdan primers if your willing to work with berdan brass.
$13 per box (assuming 1 box= 20 rounds) = $0.65 per round. I load them for about the same (about $0.60) excluding the cost of brass (since i plink with prvi ammunition, the load the 1-fired brass). Brass is always the most expensive part of reloading. As a side note i dont do it for the money or accuracy. the cost is the same and the GP11 is the pinnacle of surplus ammo. rather, i do it for bullet selection. GP11 is 175gr FMJ with BC of aprox .505 (depending on your source). Loading allows me to use 178gr AMAX with BC of .495. Compare these with ballistics software and the differences are negligible even out to 1000 yards. Why go through the trouble you ask.... Amax can be used for hunting!