They are hand fitted and hard to do as well as Colt did, but barrels are threaded on/in and can be replaced if necessary or desired. That said, they require precise fitting and a replacement barrel will not simply drop in without exact measurements and a skilled smith with the correct tools.
ETA: Since you have a nice Huntsman that you got for a great deal, you might also consider getting a parts set harvested from a beater for $150-300 on Gunbroker and building a Franken-Woodsman to suppress. New to very good condition replacement barrels are easy to find and not expensive in target, sport, and even match target configurations. Fitting one is not prohibitively expensive and buying a barrel, threading it, and fitting it will likely cost less than the amount you will devalue your pistol. Of course, it is a Huntsman, so it's not as though you're considering chopping up a Match King, but Huntsmans are equally out of production, rather collectable, and never found at the price you did. Food for thought.
Purists will obviously argue against dorking with a nice (and even a well used) example, and it will only hurt the value for Woodsman enthusiasts, but ultimately it's yours to do with as you wish. I'm with the others in terms of not molesting this beautiful pistol that you got for a sinfully awesome price - don't let the price mislead you in terms of the value of your Huntsman, which starts much higher than you paid and will only go up. If you want to suppress it, it's yours and meant to be enjoyed, but there are other options that will leave this sample intact.