Hello,
Assuming you have other details for the 2600 items, like manufacturer, brand, model, clear images, etc, which can help us to find out the UPC numbers, or at least to help me identify existing listings of those items on Amazon, I can complete this project in approx. 7 days. If you have some or all UPCs in any format (text, XML, PDF, suppliers' websites or manufacturer websites, or whatever else) then the process can be much faster. The difficulty is if you have nothing for them and they aren't already listed on amazon by others.... I think we have to discuss all these issues...
A few words about me: My main job is software developer, but the last 3-4 years I'm also working on online marketplaces, including amazon, ebay, and Rakuten Play (I started creating some programs for these marketplaces, but I have been involved in all other levels, uploading, inventory management software, pricing software, etc...)
Looking forward to hear from you,
Kind regards,
Chriskerpini