Hello,
I should be able to do this for you within two days, and for $100.00 (US).
I've been developing software professionally since 1984. I've been working with clients long distance like this since 1996. My specialty has always been interfaces with databases. I've done a lot of work on complicated invoicing systems in the past. And I've got an M.S. degree in Computer Science.
I'm located in the Chicago area.
Please feel free to write me back, even if you just have some questions for me.
Sincerely,
Jim (FRConsulting)