To clear a $650 cash bonus (assuming Platinum VIP status) requires you to clear 24550 VPPs. (This is from the 20000 needed to reach 50000 FPPs to purchase the bonus, then another 4550 to clear it.) So 1 VPP is worth 650/24550 = $0.026.
Adam made mention of it, but I think this is an error in your calculation. The 4550 to clear the bonus should not be considered a cost unless this is the final bonus you are trying to clear. If it is the final bonus, then the 4550 VPPs to clear will not be serving double duty; thus they must be considered a cost.
If you are trying to clear one, and only one bonus, then your "1 VPP is worth 650/24550 = $0.026" is correct. But look at trying to clear 2 bonuses:
You must earn 44550 to earn $1300, so...1 VPP is worth 1300/44550 = $0.029.
As we try to clear more and more bonuses over time, the 4550 will become negligible and there will be an asymptote at 1 VPP is worth 650/20000 = $0.0325.
--Kurt