Quick Shopping Cart (godaddy)

I have a Quick Shopping Cart set up through HostingDude (GoDaddy).
I am only selling one e-book (1 .PDF File).

The product description pages are all dynamic (since they could change at any time).
Also, it is set up as a subdomain of my main page.

Are there any marketing tools to work with this kind of cart?

I could either:
1. Treat it as a different site, and base my SEM accordingly
2. Say “Screw it, it’s all about user-friendliness,” and place a link on my main domain
taking the user DIRECTLY to the checkout page all ready to rock (thus eliminating more clicks for the user).

What should I do?