Not in my opinion. Sure you can post a message and have people give their opinions, but they will be all over the place. Your best bet is to use a service like
www.zetetic.com, SEDO.com, or others where you have pay someone that not only should know how to determine the real value, but also that should be respected by the seller as credible.
In my opinion, there are two areas to consider when determining domain value. One is pretty easy to understand and verify, one is not.
The first one is how much the domain is currently earning, assuming it's parked. You can take that number and expect to pay somewhere between 10-30 times the monthly income. If you can pay less than a year's income and can really verify it's earning that much, then most would consider that a great deal...!
The second one is speculation about the sales value of a domain. This is going to vary widely and is affected by many things. Conrad.com would probably sell for more in Germany than the US. A French buyer may not pay much for Ronnie.com. But a domain like Charles.com should fetch a good price from US, or English buyers.
This is something that a real appraisal service should be able to help with, to not only look at domain sales in the past for other domains, but also to evaluate the potential for this specific domain.
I still think it's a lot of guess work...
