sub-domain investors

QEIP, Domain Price Checker, and Graen no longer provide free evaluations for sub-domains. I noticed this past weekend, I wanted to make sure it wasn't an update glitch.

To my knowledge the only free online evaluations left for sub-domains are HumbleWorth, Symbolics, GD, Furm, and DynaDot. Symbolics doesn't provide a financial evaluation. Furm gives you something similiar to a ven diagram.

NamesWorth says coming soon. DomainIndex is hit or miss.

QEIP was one of my main online appraisal tools. I prefer to have more online appraisals at my disposal to give me an approximation on where to price a domain.

Questions

Do the remaining free appraisals become more authoritative?

Is it fair for a registrar to sell a sub-domain you're unable to appraise?

Will sub-domain registrations decline due to limited online
free appraisals?

How were previous sales of sub-domains evaluated?

What are your thoughts?