If you want to use Paypal for your online purchases and prices are dynamic (come from database and are not hardcoded) your need to use a a non hosted/non code protected button. Follow these steps:
- In your Paypal account (Business or Premier), click on the Merchant Services Tab and select "Buy Now Button"
- Click create a "Buy Now" button
- Enter your information to customize the button to your needs
- Click Step 2 and uncheck the "Save button at PayPal"
- Click "Create Button"
- Click "Remove code protection"
- The generated code is highly customisable and you can supply it with other attributes (html variables) from here