The appraisals are worth about as much as you pay for them. Why?
You will find all manner of values placed on any domain. The people placing values have all levels of experience and also their own bias. You will find people saying that the domain is worth X times the revenue.
So, what to do?
Go ahead and seek out the free appraisals and take the input with a grain of salt. The informal appraisals may give you a sense of the range of possible values, if you get enough input.
IF you are going this route be certain to place the domain name in the subject line of your post.
IF you are going this route the most info you might add is 1) traffic stats; 2) Overture with extension.
If you do the above you will draw out the most replies.
Don't tell anyone but I've been known to post, now and then, at other domain forums. Nothing turns me away from offering my opinion about a domain's value than a poster who doesn't put the domain in the subject line. I won't even bother to open the thread. The second turn off is someone who pumps their own domain. Why the pump? I'm not your buyer. I'm the guy you're asking for a value, so don't sell me - let me do my work without the distractions. The serious knuckleheads are those who ask for an appraisal and then debate the values that are placed on their domain.
These were the same kind of people who were selling domains like TOP100USATIRESCOOLCOOL.com(not real). The big and success players now are all automated, they don't hang around in forums or chat rooms.
Actually, back during the dot com bubble, there were a lot of knowledgable people on public boards and chat rooms. That was when the domain market was relatively new and things were inefficient. It was a pretty decent crowd, I had one guy compliment me on one of my domains because he noticed I got it after he had scanned the zone files/registry! Smart guy.
Anyways, my point is that the public boards now are pretty pathetic. I wouldn't pay attention to them.