How best track, provide report, of users arriving via my DP site

In my DP site I have administratively given selected vendors a 90-day trial Featured package. Then the idea is to demonstrate that they have benefitted from traffic coming through my site and should therefore
1) At least claim the listing
2) Hopefully upgrade to a paid Featured Listing.

My question is, what is the best way to do track all this traffic and send the client a little report? I believe this is a good way to demonstrate the benefits of a listing. I want to use this report as part of the sales process.

On the vendor’s detail page they have the “Visit Website” button. It links to the vendor’s website. I want to track when somebody uses this link.

The “Contact Owner” button currently sends an email to my account, not the vendor’s. I then forward the visitor’s email to them with a short blurb saying they received this email because of their listing on our site, along with how to claim their listing and the benefits of a listing. If they claim a listing I’ll change the Owner’s Email over to their address.

What is the best method (a program, plugin, app) to track when a visitor clicks the Visit Website and the Contact Owner button?

I realize that if the vendor has Google Analytics vendors can tell where their visitors are coming from. But you and I know few small businesses actually make effective use of Analytics.

Has anybody here used Piwik? I’ve also looked at a few plugins but before I plunge into all that’s required to find the best one I would appreciate everybody’s experiences.