Well they aren't really that "Elite" then - they're specialised. Great Guard is an example of an Elite unit - its better at almost everything other cav can do.
Bow/Matchlock monks the same - they excell in most areas (accuracy, range, morale) beyond that of the other units in their unit-type.
Hence, in all these cases, the higher price.
That is not the case with Naginata Warrior Monks and thus they should have a lower price OR get an increase in stats to justify the price.
Evan