It's no secret that appraisals are bad in the domain industry .. mostly because it actually isn't possible to be accurate when it comes to domains .. or at least not when it comes to "end user" pricing.
At the end of a day the price a domain sales at depends on how the end user values it .. combined with how much money they can realistically spend. There certainly are tons of quantifiable metrics .. but those get multiplied with some totally random things resulting in an extremely unprecise result.
Add to that the fact relatively simple algorythms can't "understand" most play on words and most "brandable" domains are pretty much impossible to assess using an automated system. But this isn't at all something that is really hidden in the industry .. Estibot for example tries to compare your domain to sales of what it tries to connect to as similar .. from a programming site it's absolutely fantastic .. but even if it were perfect it would still be accurate a minority of times with Brandables.
GoDaddy valuations are new .. believe it or not it's MUCH better now than when it originally rolled out .. but that's because a few months ago it deserved a 1/10 grade .. now it's maybe at 4. Whoever green lit that system obviously had no clue about domain sales in any way.
It's not a far stretch to say GoDaddy is a giant colossal incompetent beast .. just too big likely without anyone able to take a step back and see all the issues for what they are. I've had a couple of sessions with their development team and they just couldn't get enough of my help (literally .. they asked me for more feedback .. but didn't really offer anything in return so I can't say I'm extremely motivated to donate my time).
BUT .. they do have FAR AND AWAY the best selection of expiring domains .. a fact that gets even better with the value in terms of pricing you can get some of the domains at (look at here and realise the large majority of the domains I've listed I got for $20 or less). I sometimes selfishly think that maybe it's better they are such a mess .. as it just makes the learning curve for the competition that much harder .. and reduced competition means cheaper domains for the rest of us willing to suffer through all the problems and inefficiencies there .. lol.
Conversely though .. sometimes some domains are valued higher than others because of actual legitimate reasons not always obvious .. like traffic, PPC, competition and several other possible factors.
Here's a little tip .. A good baseline to see if you're "not bad" at evaluating domains is go and listen to all the old
DomainSherpa reviews (there is tons of fantastic info and advice in there) .. absorb what you can .. then listen to them again .. and keep listening while you buy/sell domains until you actually find comments and opinions they say and share that you disagree with (for actual reasons you can quantify/specify) .. once you have that confidence then you won't be bad (because nobody can ever really be all that good with evaluating brandable domains.. lol) .. then once you understand you can never be that good .. that's when you realise .. holy crap .. why the ____ did I buy xx% of my useless domains? .. lol
Also .. for wholesale pricing try "paper trading" .. go to DSAD aka (
Domain Shane) and check their daily lists and price them yourself .. then 1-2 days later go back and check what the names sold for. But again .. lots of factors even in wholesale to be very accurate (although it is at least more predictable than retail sales to end users).
Finally .. it's also very important to remember that "valuation" doesn't necessarily translate into sales .. a good assessment of the actual probability of the domain ever being sold.
ok .. anyhow .. good luck moving forward!