Hello !
I have previous experience with Amazon Api, i have create standalone ( Visual Basic) and Web based ( PHP) programs, that get data from Amazon VIA AWS Api and Amazon MWS api.
Can show example.
As Your budget is limited i can recommend next solution:
I will create VBA script right at excel that will get info through Amazon AWS Api.
It will be user friendly. You will input UPC if You need, press "start" button and get all to excel spreadsheet. It will handle 10 000 without any problem.
If You need somebody who can manage really difficult thing, I am right person, I am not indian who use recorded or stolen scripts, i have good background, and all my scripts work with 100% accuracy and performance.
Hope for Your respond,
Regards,
Vlad.