That is a good question.

I imagine it depends on what your selling.

What image your site projects.
Security
Trust
Value-Informative
Easy of use
Easy of ordering

I don't buy much on the internet except I did win a car bid on e-bay auction.
Seemed like a good deal at the time. The seller was well rated. The pictures looked good and were plenty. I am selling it know as I bought a Van...well 2000 Chysler Cirrus loaded...LOL.

I look for information about products and price but like to see the product ya know feel touch etc..I hate returning things thru the mail. It might be intersesting to see what people buy-like a list--they could get long.

Car e-bay
Some clothing - e-bay
Instructional Information medical from England- Doctor-good service for frozen shoulder
Dog stuff- private company------ yes for my dog
Some business supplies- wood refinishing various private companies.
Cell phone used -e- bay just ok
Prescribtion Drugs- Canada cheaper.