While (on Namebio at least, I realize their coverage of new gTLD is far from complete) there are only 11 .fit sales listed, but gym(.)fit went for 2.5k, stay(.)fit for 2.4 k and eat(.)fit for 2.0k. The top .fit was elite(.)fit for 10k (zumba(.)fit went for a bit over 100).
So overall I would think you should be able to get about 2.0k for now(.)fit, but with limited number of sales in that TLD you may need to be patient to get the price it is worth.
It is a superb domain name in my opinion.