After receiving a request from a person interested in buying one of my sites, they requested that I have it (the one they wanted to buy) appraised. Went ahead and did that… and was pleasantly surprised by the results:
ViralIncome.com, while Leapfish valued it at around $6,500, it was actually valued at $10,500 
(Certificate here)
Because I was doing that one, and the company offered discounts on multiples, I decided to get the true value of another one, BusinessAndMarketing.com.
Now I know it wasn’t valued at the $175K that Leapfish said it was (they rank on keywords), but here’s what the results were for BusinessAndMarketing via the same above site, CertifiedDomainValue.com gave me the certificate valued at $27,900. (I don’t know if its just my ISP or whatever, but there are days I have trouble loading their site, so if you have issues with that, try a different browser or reload the page).
Both sites are up for sale on auction, and as of next week, if not sold for a reasonable offer, I’ll consider posting it on Flippa.
If you choose to sell any domains of your own, it is a good idea to get an appraisal done, but make sure you choose the companies carefully, not all have good reputations.
Amber