Merchant Services through the bank can be very expensive to startup, with initial costs, fees, machines etc before you’ve even taken your first payment.

Paypal may cost slightly more on a  per transaction basis but there are no setup costs and you only pay when you get paid.

Here are some useful links for setting up merchant services with PayPal.

PayPal Developer

PayPal Payments Standard Overview

HTML Variables for PayPal Payments Standard

Payment Data Transfer

Adding PayPal to a 3rd Party Shopping Cart

Using your PayPal Account Profile

FAQs

IPN Overview

Technical Documentation

Express Checkout Integration Guide

The Luhn Algorithm

Testing PayPal Payments

Test the Rest API

Setup your Sandbox Test Account

Testing Classic API Calls

Test PayPal Payments Standard Buttons