Cost of Parts
Given that that these bolts are now a SIDS item I highly doubt that Cessna will only sell 500 per year with two per aircraft. Consider how many spring gear aircraft are still in existence out of a production run of perhaps 20,000 pre tube gear models. The engineering and paperwork was all done long ago and I would be highly surprised if Cessna didn't put a lot of them on the shelf in anticipation of their use over the life of the product. With a life of three years or 1000 hours Cessna can certainly expect to sell more of them. The Americans are getting their asses kicked by the Chinese because they fail to realize that they are not delivering a product at a reasonable price. You can make the safest plane in the world but if your customer cannot afford it you wont make any aircraft sales. They have failed to innovate and have not delivered a successful new piston type since their heyday in the 70's.