The gun is BIS as far as raw damage goes at 59. However, the level 58 version is the easiest version to obtain, making the market value on it not too high, compared to the price it'd be at either 39 or 49.
I think 2,500g is a reasonable price for it. I bought one for 2,000 a few days back, and have looted 1-2 of them from random mobs recently