Typically 440 rounds in a 7.62x54r spam can. If they are going for $500, I have one for sale. I won't hesitate selling one for that. I might even have two for sale. I think I have three of them. Thought I was buying x39 with the third one, oops.
I wish I had the $500 to give to you! Ammo prices are crazy and even the ammo prices on auction sites is super inflated.