Opt in for downloadable pdf etc.

Hello,
I’m looking to get a “free download” widget/html code on my front page. The idea being the site visitor sees the “free offer” – gives me his name and email and in return gets to download a pdf (typically an e-book or brochure).
Now aweber and mailchimp do wordpress integrations to effectively achieve this but I’m not keen on the costs involved. I’d much rather implement it at little or no cost and if it proves successful then I could move on to a more commercial solution.
Any ideas as to what I need to do ?

Cheers

Gavin