You may pay more than the domain cost itself to these 2 doamins. One should never trust a company without proper verifications. http://www.DomainMart.com and www.EasyNameSale.com are the two domain names appraisal websites that one may not trust without a reference who had got appraisal values in the past and it is very likely you would be getting appraisal value that would be lesser than the value of your domain itself.