It's very hard to price the work of another smith. A lot depends on the local economy and the individuals level of skill. An average local smith will usually cost less than a prominent pistolsmith.. In this area, assuming its a direct switch ie. a Ruger replacement barrel, somewhere between $50 and $200. Please note that that is just a tiny bit better than a guess as I am not a professional smith, but time is money. In example I broke the handle on my Ford F150. The replacement part was $16. It is a fairly easy 1 screw, 5 minute swap that doesn't involve taking anything apart just remove the screw and broken tailpiece and install the new handle with the screw. Tools a single socket and handle...they asked a bit shy of $50. This sounds ridiculus and it is but they have a minimum 1 hour charge..wanna bet what their hourly rate is?? Goof luck..