If there's a way to do this, I'd love to know. I've wanted to do this before to avoid overdraft fees (I have an account I use specifically for buying games). AFAIK though, there's no such thing.
Well, if you confirm and validate your account you can. At least if I understand what you want. I can go and add money from my bank account to my paypal balance. So let's say I want to have a paypal budget of $50 for the next 3-4 months for my bundle purchases. I just transfer 50 bucks from my bank to paypal and will have the $50 in paypal credit sitting in my account whenever I need it. When I pay for anything through paypal, it will default to my paypal credit until I run out or don't have enough - then when I try to pay for something it will show something like:
Paypal Credit: $1
Remaining Balance Withdrawn From: Wells Fargo Bank Account #
Then when I see that I know I am out of cash so I either don't make the purchase or know that my $50 have run out.