Cruise control

[Houli715]

I have a 1992 Nissan 240 SX SE convertible in good condition that I purchased from a private owner about two years ago. The car is automatic transmission. It came with cruise control. I actually tried to use it early on shortly after my purchase. I was on the highway going around 70mph and the cruise control light lit up after I hit the correct buttons in attempt to set my speed, but it didn't seem to hold the speed on its own. I attempted to set it again many times. The first few the light lit up to indicate it was working, but it failed to really hold speed each time. Finally the light stopped coming on. I accpeted that fact that it must be broken, which is a shame. I wonder if it was in the process of going out when I first tried it out because the light actually used to turn on, and now it won't even do that for me. I wonder if it would be costly to fix it? I also wonder if it is easily fixible since it semi worked not that long ago?