Broken steering cable ???

I have a Yamaha 90 2 stroke 2004, my steering locked up wile on the water. I tried to turn the whee as to get back to the boat launch and something let loose. Now the wheel will spin freely and indefinitely. I assume the cable is broken. can any one tell me how difficult of a repair this is going to be? How much $$$?????

[boats.net]

You can get steering systems for about 100.00 or so, not sure which system you have.