Alan, that's cheap in comparison to a Hellfire
A seven round APKWS/Hydra pod is a lot more bang for your (
insert local currency of choice here) and it gets you 7 targets instead of 1.
I'm pretty sure that $900 is for one of the unguided ammunition types - and probably a simpler one at that.
AIUI a single HellFire is in the 100,000$ range (similar to the longer ranger Brimstone)
and an APKWSII guided Hydra around 30,000$ (body, seeker and explosive)
Barely a three to one advantage, though BAe who make the APKWSII claim faster reload & other cost savings.
Compare that to a 120mm guided mortar shell at 10,000$.
This is for what is essentially an adaption kit to most existing bombs (similar to early paveway models)
Presumably the 81mm equivalent is even cheaper - known as the Roll Corrected Guided Mortar in UK service.
though in true military purchasing style the equivalent US 81 mm Mortar system goes for added capability not lower cost.
Created for the US Marines in aproject called ACERM it still costs ~ 10,000$ per shot despite the smaller warhead.
However the initiative does include :-
a new light weight tube
nearly doubled range vs the standard 81mm bomb
both GPS and laser homing
and will be used with a low cost drone as designater.
The basic controller is hand held giving organic PGW fire power to smaller groups of soldiers
and the Marines are also planning a "battery in one tube" approach ... MRSI (Multiple Round Simultaneous Impact)
though this may need an even more complex and expensive ACERM X round :-(