What type of payment is best suited for low amount transactions in a e-commerce-like website?

We're building a kind of e-commerce service which sells only one product.

That product will be priced around 1.5€. Our paying users will checkout approximately 3 times a month. Each checkout should be between 1 to 3 products (1.5 to 4.5€).

Due to the low price of our products, we're thinking of two totally different payment methods:

  • Pay the right amount for each checkout
  • Credit your account once in a while, and spend that credit at each checkout
  • ... anything else you can think of ?

We would like to understand what's the impact to choose either one of those methods for our users: feelings, understanding, behaviour, boredom, expected AARRR metrics impact...

We thought about testing both but it might get too costy for us right now and we need to make a first choice, as informed as possible.

Do you have any input/experience to share on this? With papers or articles as source?