Email appending database

I would like to have an excel spreadsheet-type system developed that appends emails to contacts. There are two ways this could be achieved - the first is to refer to our database of known patterns and the second would be to review common patterns to construct email addresses e.g. below. The minimum data would be firstname, surname, company, business url. If anyone has worked on a similar project and/or can offer a pricing guide for a project of this nature, please bid

Example patterns:

mlagrande@example.com
michelle.lagrande@example.com
michellelagrande@example.com
lagrande@example.com
michelle_lagrande@example.com
m_lagrande@example.com
michellel@example.com
michelle@example.com