What I would do is get yourself 100 rounds or so of the PPU ammo, shoot those then reload the brass. BTW 7X57 is also known as 7mm Mauser.
PPU ammo should be $15 to $17 per 20
Dies hereBullets can be had from many sources
Powder will depend upon type and weight of bullet but expect to reload 150-200 rounds per pound of powder
So our first hundred rounds will be $75 to $85, to reload that will be about $50 but those will be so much more accurate. Ill help you reload em once you are ready.