Instead of stopping the surf for cash try doing the follow:
Have an adjustable rate based on income of the site, example as follows:
Something like vagex.com does.
They take total income (cash in payment accounts (after their pay is taken out) minus server costs (next payment due).
Then they adjust the exchange rate to have the total credits in the system match this total. (they do it daily, but you could do it weekly or monthly)
example would be:
total sites views in the paid to surf since last payment: 100,000,000
Total in payment accounts (after expenses) 1000.00
then you would calculate the exchange rate as follows 100.00/100,000,000 so the rate would change to .00001 per view.
this would allow anyone that wants to surf for cash, and keep the site viable, because the rate takes into account members that will probably never reach payout.
Calculate the new rate after paying any pending requests.
Hopefully you have the site debt already calculated in your back office (admin section), you could have the programmer code it to calculate the following:
Total paid to surf pages surfed since last payment (this is a total of all members combined)
current exchange rate
Total site debt
plus you would need a section that you can change the rate to pay both dollars and euro (would be best if you calculate the euro rate first, then the dollar rate based on the new euro rate:
This would make the site more busy with surfers. I was surfing around 3,000 or more per day, but it is not worth my time or effort to surf just for credits, and I am sure that is the case for a few hundred members.
Even if the rate was only .02 per 1,000, or even less, some money is better than no money, especially when you have the reputation of paying.