The threaded alloy uppers and/or integral suppressors for the Ruger are awesome but not cheap.
As I pointed out above, one of the main reasons for the high cost is that the upper receiver and barrel unit is legally a firearm. Ruger did not design the Mk-series with easy barrel swaps in mind.
On the topic of threaded barrels... I believe that a factory threaded barrel unit for the 22A would be a great idea and would increase the market potential of the pistol. (S&W Management, Are You Listening?)