If your button code needs are basic, use the online button creator. By default it generates "hosted" item button code where specific variables are stored on the PayPal Servers. This makes your code tamper proof. The online button creator also has the option to encrypt the item button code.
As for using any type of scripting, you can't really hide anything because you still have to use the recognized PayPal variables.
Don't get too worried over trying to protect the item button code.
It's not really a problem using clear text item button code. Yes, it's possible a not so honest customer can change the amount of your item. However, you are responsible for reviewing the transaction and you have the ability of accepting or not accepting the transaction. Should you see that something is not right with the transaction, you simply refund the money back to the not so honest customer. A not so honest customer will not dispute your decision as he or she now knows what you know.
It's important to understand that just because your code is hosted or encrypted, this does not stop a not honest customer from simply filing a claim and chargeback after a successful transaction. Should that happen, it's quite possible that the not so honest customer will end up with both the merchandise and their refunded money. And unfortunately this is a bigger issue than trying to hide button code.
Using clear text and PayPal's Website Payment Standard is "secure" from the customer's point of view because the transaction is processed on PayPal's Secure Website. No customer credit card information is shared with you. For example, there's no way you would even know what credit card the customer used. You simply see the funds in your Account, no questions asked.
Regards,
skier
