I was wondering if anyone knew of / had used low cost Inertial Navigation Units that they might recommend. I am looking for something usable off the shelf, preferably with digital output. I do understand that 'low cost' for an off the shelf INU will still be at least several hundred dollars, but am looking for something under $2000. I do not need a system with built in GPS unit, the system is going to be used in an underwater vehicle, so the GPS will be fairly worthless.
Any help here would be appreciated.