This is my area of expertise.
But first I need a working copy of your application, all files *.exe,ovl,dbf,dbc,,etc.. ).Only after executing, going through the working of the application, understanding the logic, studying the modifications, enhancements you need, can I say anything about how much time it takes to complete the work.
I have just completed a similar Point of Sale project for an Automotive Spare Parts Shop, I can't provide a copy, but can send a few screen shots of the application developed in Visual FoxPro 9.0.
If I undertake the work after studying your application, I assure you I will complete it to your full satisfaction, or you pay nothing.
Though I am new here at "Freelancer", I have clients from U.S ,who give me continuing work,since they found my work satisfactory. Visit my face book page to see what they say about it.
You can contact me either through, email, or skype text chat only to discuss about the project,
since I found it better to keep a record of the discussion.
Regards,
George.