Interestingly there are a number of US companies funded under the DARPA Ocean of things program to do just this, and then some. For a company to accomplish such

Interestingly there are a number of US companies funded under the DARPA Ocean of things program to do just this, and then some. For a company to accomplish such a task the cost is greater but still less than $1k per unit. Everybody wants to put more than just A GPS out there. For one reason, we already understand mesoscale ocean currents well enough that they are not interesting on their own. Also the per buoy cost is high enough that hey, let's just add one more...