Kendra Wilkinson's "Kendra Exposed" sex tape has already earned the amateur porn star a whooping $680k and the video hasn't even been released yet!

Kendra will get her check this week and there are "many more" Kendra sex tapes to come. She's making her mama and papa proud!

Kendra's ex-boyfriend Justin Frye -- the man who orchestrated the deal with Vivid -- sold a virtual library of home videos that numbered as many as 20 tapes and tens of hours of content.

It has set up Vivid to release a series of money-making sequels to the Kendra Exposed premiere, which is scheduled to be released on DVD this week.

I find this all very disturbing. Kendra Wilkinson's sex tape is like kiddie porn. She looks friggin' 14 years old in some of the stills and I know that must be a reason why some people are purchasing her sex tape, which just makes me nauseous.