Legit? Seems cheap

Interesting.
Assuming everything is verified re: ownership/use, Value is in the eye of the beholder.
Personally, I would get a new T-Funk for less than half, but to a Collector, its different. An "inferior" Vintage bass that is not built as well several of my modern axes, but costs 20X more, etc.
A far as Celebrity, that really means nada to me. I wouldn't want to have to gig with either Jaco's or JJ bass.

If someone wants to drop 5 large to "own" & honor a piece of Jaco pastorius- cool.

 

This has been on the market for years, it will not fetch this price or more.
Though he has been dropping the price. It was $15,000.
From 2004 Buy Jaco's amp! Only $15,000

 

I bet Jaco is laughing his butt off over this one.

 

Might give it a go if it makes me sound like Jaco.
On the other hand, for $30-$40 used, I can get a multi-effects pedal with a setting that will make me sound like Jaco.