a blank 28" or shorter will cost about $300 or so depending on who you get it from.
Wait time will vary from on the shelf to maybe 6 months.
look at www.6mmbr.com
in their classifieds and they are normally there for sale at regular prices.
Look at each barrel maker and decide on which one of their contours will work for what you want and what twist. They have a chart on their sites.
DO NOT try to take it off yourself. If you are asking these questions you do not have the experience and tools to do it correctly in all probability.
Plus they will not charge to take it off. Just send/take the barrelled action to your smith.
Cost to rebarrel and crown will run approximately $200 +- a little either way.
Decide on the reamer you want to use. ie what throat length and min or max SAAMI.
Are you shooting the 130s or the 140s? that will determine your throat for example.
140s will require 8 twist and longer throat.
130s can be around 8.5 to 9 twist and shorter throat.
talk to the smith about which reamer he has and you want it no neck turn and min SAAMI probably. That may determine which barrel you get. Plus see what his wait time is for simple rebarrel and chamber.
while he is at it, I would have him use a trued recoil lug, face the receiver and lap the bolt lugs (another $150 +-)
Now, is your stock opened for that barrel contour? Maybe/Probably not, so send the stock and have it bedded ($80-150)
Several good smiths here for sure. Just call/email and ask the questions.