I can do this for you for 100USD(4500+500PHP) in 3 days, no problem.
The thing is I will do it in Visual Basic, and the excel would be more like an array view(rows and columns) but it will save data to a excel worksheet(excel file will be the database for my program; it will read/write from/to it).
First I'm going to need to see the excel file. After I will do a interface that will be shared with you for approval(you must agree on). Then I will code on the buttons and make rules for logged in users. Finally I will give you a admin interface to add/edit/remove accounts. If you want to go with excel file it must be on a share server.
We can go with SQL database(same price) and it will be much harder for someone to edit it, without using the program. From the program you can export at any time a excel matching your initial format.
PS: I'm going so low on prices because I'm trying to build a reputation on this website.
Hope I'll hear from you,
Rares