Hello,
I feel like I can help. I would do the program in Python. I have a lot of experience with Beautiful Soup, which I a library for pulling and navigating through HTML.
I do not have that much knowledge about the eCommerce sites, but would like to learn more about them. I can draw from my experience operating bookmaker websites. For me it is a project to begin my Freelancer career(I have a lot experience otherwise), therefore it is not imperative I make a lot of money. I set the delivery date for 7 days. I believe this is reasonable, even though I have not yet made a concrete plan, it might take me a lot less.
You said the payment will be after completion, I agree with that, however you have to deposit the requested amount.
Do not hesitate to contact me.
Best regards,
Borut