A Recomended 27mhz transmitter + receiver?

Hello i'm trying to get a trying to get a transmitter and receiver combo (preferably a transceiver for both way communication) for an underwater RC vehicle that is able to interface with the Arduino with relative ease, 27mhz seems to be the lowest common frequency to use with the most water penetration but the problem is i don't see any 27mhz communication modules, only pre-built controllers that one must find a way to hack to use (not a bad idea provided it is cheap and relatively easy to use).

So any recommendations on popular 27mhz transceivers? i'm looking to send custom controller data to an rc submarine, while also receiving sensor data at a relatively fast update speed.

Ebay has lots of 27MHz RC stuff, which you could hack or "misuse". For example, a 3 channel servo setup could be used for 3 data channels instead.

I doubt there is much in the way of general purpose communications modules in that frequency range, because most uses would probably be illegal.