Excel Workbook sharing

Currently, we have approximately 15 consultants. Each consultant periodically emails a workbook to update status of projects they are handling for us.   Some consultants have a workbook with >1 spreadsheet in them. Each spreadsheet means a unique project. We are talking about 50 spreadsheets altogether, when transferred to a single workbook. The contents of each spreadsheet are relatively small - about 120 rows x 12 columns. Our objective is to stop data transfer through email. We plan to have a single workbook online. All consultants will be given a common link to the online workbook including login access. Consultants will log on using a username/pwd in order to access his/her related tab (spreadsheet) in the workbook . Other consultants spreadsheets should not be visible/accessible to this consultant. An admin should be able to admit new users and control passwords and have viewing access to all the spreadsheets. We will also need reports from the workbook showing project completion status, consultant performance etc. We can send all the workbooks so you can consolidate in a single workbook. Our budget is limited since it is a personal initiative. Please give us your best offer and how soon we can expect completion based on the requirements above.