1. 1st and 2nd gen barrels are the same 20 TPI x .695” + or- tapered thread, so they do interchange.
2. You can find barrels and cyls on ebay and gunbroker that run in the $150 each ball park for nicer condition. Some that have these are:
Jim Martin – Colt Forum member
Dave Lanara: www.davelanara.homestead.com
3968Turnberry Drive, Medina, Ohio 44256 330-952-0031 shop, 216-780-3729mobile.
Peacemaker Specialists: http://www.peacemakerspecialists.com/parts.html
Colt Parts: http://www.coltparts.com/parts1.html
3. No new 1st or 2nd gen parts are made or re-man. Some Colt clone parts will work if you don't have to Colt parts.
4. You need to study and know what the correct parts look like. True 2nd gen cyls will have a rampant Colt logo on the rear face, for example.
5. That's about top dollar for a NOS barrel and if you confirm the threads are as I stated above, yes it will fit 2nd gen. Recognize that barrel addresses and caliber markings vary with the barrel vintage.