If I went for this, I'd get either websiterank.com or rankwebsites.com instead. The latter is for sale for under $4,000 so I'd just drop the money on that. There's no point in compromising the quality of the domain at this price. siterank.com and ranksites.com are also viable alternatives.
Also, websitesrank is not registered in 5 extensions. It's only registered in the .com. I'm assuming you're referring to dotdb's key-phrase matching, where websitesranked.com, websitesranker.com, websitesranking.com, websitesrankings.com.
Also, the age of the domain is 3 months, not 16 years. If the domain has been dropped then the age resets.
This will be a difficult sale at any price-point I think.