Paypal IPN in a PHP Form - repost

I already have a php form done and it sends out an sctivation link after the submit button has been clicked. So what I want is after login info and personal info has been entered the user need to pay with paypal and only after that they can hit submit button and the activation link will be sent out. Also the details entered by the user will be stored on the MYSql database. ( this is already done in the form itself) Should be a small job for someone who know what he is doing. My budget is maximum $15 and the job needs to be completed in 1 hour. Please only bid if you can start right now.