Our new Vibracart Pro shopping cart supports product options that change the base price of the product which is what I think you are asking for. It comes with a set of stacks so that it works seamlessly in Raidweaver too. Checkout is via Paypal and / or Stripe with SCA compliance.
You didn’t mention if you are selling a download or a physical product? Vibracart Pro supports both anyway and can handle delivery of downloads as well as shipping and tax etc.