Bought 500 rds of 70s German military surplus 7.62x51 and it was as good as the high end ammo as far as accuracy plus my M1A1 loves it.
In the late 90s, you could get nice wooden crates of 1000 rounds of Austrian made Hirtenberger NATO spec 7.62x51, Boxer primed (so reloadable). Inside the crate the ammo was in 20 round boxes in nice heavy rubbery plastic 200 round battle packs (so 10 boxes) with handles.
Typical price at the time for the crate: $175
< sob, sniff>
I wish I had bought 100,000 rounds or more as an investment.