Having your barrel threaded and tubed would probably be cheaper. But the barrel would be pretty thin at the muzzle.
I had my 1100 tubed like this. It works alright, but it is very thin and easily bent or torn. I have put hungreds of rounds of buckshot, slugs, and target loads through mine without a problem. I tend to use the Modified tube the most but will switch to the Imprved Clinder for slugs when accuracy is important.
Talk to your gunsmith about this. See what he thinks.
Neil Casper