Hi there,
I'm quite familiar with integrating payment processing with websites. I've done so in the past for Paypal, 2Checkout, and a few others. Though I've not yet done this for the three websites you mentioned, I had a quick look at their documentation, and they all support an API and have good documentation, meaning I'd have no trouble integrating them, as long as you have an account on all three sites.
I will provide you with regular updates. I speak fluent English and I'm available for chat for most of the day. If you'd like to get started, I can have this project done for you in a maximum of a few days, possibly this weekend.
Cheers,
Ali.