the lowest ive seen was $1400-1500, but your price is certainly still on the low side, as ive seen $2,000 - $2,200 as well. also depends on the case (soft case is collectible and often gets sold off on used ones) and what else comes with it, but maybe thats not an issue if its NIB. the roll marks will also determine its value. ie . Mk 23, Mark 23, MARK 23. - cant remember the difference offhand, but there is a difference in issue date, rarity, etc.
edit, from WIkipedia:
-Military versions of the firearm have the writing "MK23 USSOCOM" engraved on the slide
-Heckler & Koch has offered the MK 23 on the civilian market and law enforcement as the MARK 23
-According to the Operators Manual,[18] there are few differences between the civilian Mark 23 and the government MK 23. These differences are the slide engraving "Mark 23" which is only for the first half of the first year of production in 1996 (KG date code), the roll-mark "MARK 23" which is for mid 1996 to now, these instead of "MK23 USSOCOM", Matte vs shiny finish for different civilian years, tan vs black frame (500 tan ones were made), and a barrel conforming to SAAMI headspace specifications for the military vs civilian made, as the military barrels were made to allow ball ammunition to work more reliably.