I use AliExpress (uses AliPay) all the time and have brief experience with the API. I'm a professional PHP developer and I know what I'm doing so I'm confident I'll deliver an excellent, fully functioning module that will work.
If you have any questions feel free to contact me. I note you're UK based so if you're in the Manchester area, I'd be able to develop on site or discuss any further projects with you in person.
Thanks,
Ruby