[dfariswheel]

One "indicator" about Colt grip originality is the rear side plate screw........
On models shipped with Target grips the screw is a flat head.
On models shipped with Service grips the screw is a dome head.

This is not a 100% proof since screws are easily changed.
It's common today for Colt's to be robbed of the valuable Target grips for separate sale to increase the profit and a gun with Service grips and a flat head screw is at least an indication the original grips were switched.

Original Trooper grips would have Silver Colt medallions.

Features that would increase the value are a gun with Target hammer and Target grips. Service hammer and Service grips might lower the value just a bit.
I don't even try to keep up on Colt values, but I'd think a genuine 95% all original Trooper would be a good buy at that price.

 

[dfariswheel]

As above, the grips are not original Colt...... the same grip is being made by Altamont, so non-original grips is a down check on value.
Also, if the sides of the hammer are blued the gun has been refinished, a major down check.

With that said, the Trooper has the same frame and action as the Python and is often called "A Poor man's Python", so you get the benefits of the Python in a far less expensive package.
Whether the gun is worth the asking price is something for you to decide, these Colt's aren't going to get any cheaper in coming years, and today's "too high" will be tomorrows "Great deal".