I currently have a review of a niche product on the first page of Google for "product" and "product review". It's a bit early to say how conversions are going now, but I thought to improve with a rebate offer.
I think you typically want to tell them to contact you after 60 days (to avoid them getting it refunded) with their paypal transaction number and so on. But how do you set this up on the page? Just give an email address? A contact form? Does anyone do this and want to show me an example.