superchargers cheaper to fix? Completely depends on the how they blow up. A rebuild kit for a turbo is only $100 for most turbo's. But if you destroy the housing, the center section, or the turbine/compressor itself, well, all of that is a different situation.
I would bet its pretty simular on a supercharger. But then, the preference is to design the system and tune it so thats not something you ever have to worry about.
My first attempt at a turbo system (home made) I guess I wasn't careful enough while welding, to keep the oil galleys taped off while welding everything together. I got some slag into the bearing area of the turbo and blew it up...not once, not twice, yes, three times. Let me tell you, that gets expensive REAL fast. Three turbo's within a week!
Needless to say, I was a LOT more careful on every project I've had since.....and now I run a filter on the turbo input. Its amazing how little metal it takes to completely destroy a turbo in seconds. I have thankfully had no problems whatsoever since then.