What is the usual value of a Fit bike pro bmx second hand? There are some photos of the bike http://imgur.com/a/rIozR 

Can I get a rough value of it?
$50 max. First, take some real photos of the bike. Fix the lighting and photo the drive side. I can't say that loudly enough, NDS photos baffle me. 

Fitbikeco has a fine reputation but that looks to be a pretty old model. (Do you know what year it is? That is obviously helpful.) Strikes against it just based on the photos:

Not microdrive (correct me if I'm wrong).

Cranks and bottom bracket are throwaway.

Frame is probably hi-ten (to get $100 plus for a used bmx you're gonna need cro-mo).

That front tire is some sort of bargain store replacement.

The way the brake cable and straddle are sagging makes me question the maintenance history.

That seat is at least three generations behind.

You don't name any components which means that are all stock with no upgrades/replacements. 

You might get $50 if you're in a small market and someone has $50 max to spend on such a bike and they don't feel like negotiating or waiting (for you to drop the price when it doesn't sell).

But good luck. Clean it up, lube it up, take some good pictures, and write a solid ad.