When I started buying domains, there was no forum, no appraisal services that I know of. You were on your own. Today there is much more information available. In theory it's a good thing for the newbies but domaining has become very competitive.
Unfortunately, there is a lot of bad information/disinformation too. For example, we see too many beginners buying domains based on what automated tools like estibot suggest
Or using metrics that are hardly relevant.
You need to learn for yourself what makes a domain valuable. An automated appraisal is not going to teach you anything, even if it had an ounce of credibility... Do your homework and see what sells and why.
Be smart, don't just learn from your mistakes, learn from the mistakes of others
The best appraisal: a sales invoice :yes: