As much as possible!
Spend every penny that your budget will allow, period! I am not trying to sound foolish its just that you get what you pay for. I realize that most of us (myself included) fall into the $100 to $300 dollar range on a scope. There are excellent scopes out there for this kind of money. It's better to wait a while and buy one when funds allow. I have missed an opportunity because of a fogged scope, lesson learned! Doug.