I saw your link and thought the basic info was interesting. When I went to order, I notice 'TIP' ... WTF? 20% even. I know you can turn it off, but it highly offended me, for the following reasons:

1) TIP - To insure prompt service - its an online order. What no tip maybe obtain the material through a dial-up modem?

2) It is a course ... Next thing you know my rent due will come with a TIP request.

3) You never TIP the owner. Tipping the owner is an insult to the owner.