Hi,
I am an experienced web developer and have also been a dealer of computers and parts. I have also checked your spreadsheet file and understand the requirement very well.
I will create a simple but effective system for you that can be managed from the front-end itself. The system will be ready in one working day, then by the time you do a test-run on the second day, I will complete the user documentation.
Code will be documented in-line. I will be using Php, HTML, CSS and JavaScript. MySql will be the database. If you want, I can also use WordPress and do the custom coding required within its framework.
I would recommend using WordPress, as you can easily extend functionality whenever required, using plugins. I am an veteran programmer who likes to do his own code, but why re-invent the wheel? WordPress provides a core CMS platform and excellent extendibility.
Please feel free to ask any questions you have. Look forward to hearing from you and possibly doing this project.
Thanks,
Srinivasa Rao.