Can I refer my site visitors directly to a particular product page at Namecheap?

Yes, you can. To do this, just make a note of the product page's URL at Namecheap.com and add to it your affiliate id as a query string.

For example:

To refer users to our SSL certificates page, your referral URL should look like http://www.namecheap.com/learn/other-services/ssl-certificates.asp?aff=1 (where aff=1 is your affiliate id).