Simple web ui to upload spreadsheets and compare values between them

Hi everyone,

We'd like some help putting together a front end, and back end process that will allow a user to do the following in brief ..

1. Upload a selection of csvs, xls OR xlsx files.
2. Select which columns in each of the files contain the values we'd like to calculate on.
3. Have the results from the calculations made available to download.

Please see the attached file for more detail on what's needed.

Kind of need this doing quickly. Hopefully that doesn't sound unreasonable. And I hope the budget is also fair.

Look forward to hearing from you.