Amazon Payment gateway

We have a website that we are trying to get Amazon payments to work on. We recently hired someone who said they can help get it working but they have not yet been able to show us it working. What we need to do is be able to change a price so we can do some transactions to see this working. This is what our developer is asking we look for in someone: "[login to view URL] page show a random number <?php echo rand() ?> And set a payment $0.5 and I can use my card and pay and see in the response page (while will be after payment, that mean after [login to view URL]) that rand number printing and ask them to modify cost" If you can help please bid and we'll talk tomorrow. We work from 6am PST to 2pm PST. It would be easier if you could also be on during that time so we can work on getting this done.