30 a shox for the rebuild is the going rate, are your sleds the X package?
push down on the back of the sled, does is come back up? there will be a pogo like feeling to the rear. take out the shoxs and push them in listen for a hissing sounds or leaks around the shox shaft. if you can push them in and the shaft does not rebound they are blown out. you have to be the judge on the rebuild.
ski doo doesnt use precision skis anymore, I would recomend C&A or SLP.
http://www.proskis.com/