It's not that o.boutique is a bad name. It's fine.
As others have mentioned, there is a surfeit of domains in these new vanity TLDs, which tends to reduce market value. (Same demand as always but greater supply.)
The real problem, however, is that appraisals need to be based on sales data. And there's virtually none. I can't remember hearing of any .BOUTIQUE sales yet. Extrapolating from a few headline-grabbing sales in other extensions is very shaky ground.
In 2 years, there may be enough data to appraise this domain. Today there isn't.
Any answer will be along these lines:
(A) Unknown
(B) Zero
(C) Statistically unlikely possibility of a sale, growing less and less likely as price expectation increases
Don't ask for appraisals on the new extensions. Look for buyers to sell to today, or else content yourself to wait a few years for some unknown person to call you.