Well,....In my humble opinion, there's a substantial difference in cost (typically) between installing another surplus or replacement barrel on a $40 Mauser action and buying a new sporting rifle (unless one is dead-set upon having that stainless steel Shilen barrel attached to their old Mauser....oh yes, some day....).
Regardless of the cost factor, there's a great deal of personal satisfaction and sense of accomplishment involved in repairing and/or customizing an "old war relic" which has outlived its intended purpose, service life, and possible collector value. I cannot say that I remember the last time that I picked up my Winchester Model 70; however, my end of the workday therapy often includes handling or working on an old Mauser or Mosin, or simply contemplating another project. Not to say that I'm ready to give up the Winchester, it's just that it is, in a sense, too easy.
Why did we expend billions of dollars and the lives of three brave astronauts in order to bring some rocks back from the moon ? We could have shaken the rocks out of Bill Clinton's head for a lot less.
