I don't use this feature, hopefully someone who does can give you a better and more acurate reply.
As I understand it, if you pay on a "per click" basis you need to be very careful. You may find yourself paying for viewers who are not in your catchment area. You will also get caught paying for other people who are just "browsing", this could end up being expensive.
I personally believe the best way to get hits on your site is to target people you want to view it. Make sure your website is on EVERY piece of literature no matter what it is, tickets, leaflets, invoices, business cards, vehicles etc... this way the people visiting are the ones you want visiting and you will get a better hit/sale conversion.
Have you asked some of the guys on here who make and design websites? they may be able to give you better advice?
regards,
Trevor