Email address capture

Hello,
I have an excel spreadsheet with 2800 business contacts for which I need email addresses. I already have the business name, tel. no on an excel spreadsheet but now need the contact email address for each.This will likely involve the manual typing of each business name into a search engine to get the contact email address. The majority of them should have own website. The deadline for completion of this job is 5.00pm GMT 14/10/10.