Thanks for the additional details. For the rights scope, I’d be looking for an exclusive transfer of the project and the rights you own in it, including the source files and the right to modify, expand, rebrand, publish, distribute, and use the project commercially.
Since you mentioned there are no third-party assets or dependencies, I’d also want the transfer to confirm that the included project materials are either your own work or otherwise transferable for commercial use.
For payment, PayPal Goods & Services would be my preferred option if that works for you. Given the small purchase amount, I think that would be the simplest way to handle it.
If that rights scope and payment method work for you, I’d be happy to move forward and keep the terms simple and in writing before payment.