If you load up Cafe World and click on the tab of the game window that says "*SALE* PayPal", you can buy more Cafe Cash (the premium virtual money of the game) for the same amount money, which involves payments of $5 to $150 USD. The offer has been active since April 22nd, but it'll only be in effect so long as Cafe World says it is.
The Terms of Service for this offer states that you must have a US PayPal account in good standing, and you're only allowed a maximum of two discounted purchases, so think carefully before you make your transactions. $5 USD now earns you 31 instead of 25 Cafe Cash. And $150 USD has the best deal of 1,600 Cafe Cash, instead of the usual 1,250 Cafe Cash.