Originally Posted by therewolf
7.62x39 is cheaper and easier to find.
5.45x39 is smaller and easier to shoot...
Not so much. . . ?
The 5.45 x 39mm is the cheapest and most abundant in surplus right now. They can be found for as little as $140 for a 1,200rd case. And American manufactures (Hornady) are beginning to pick this cartridge up and are making great ammo. Mags can get scarce though.
The 7.62 x 39mm is still inexpensive at about $200/1000rds. Mags are plentiful and the round has excellent penetrability. It is abundant as well in surplus and made here in the US as well.