Welcome! Please spend some time reading the FAQs and Help sticky, the Accessory Barrel info is in there, new is relative, you can find out when it was made by comparing the serial number prefix with the build year info in the FAQs, H&R won't fit any high pressure * marked barrels on the accessory barrel list to frames made before 1999, but if it is a 2003, any barrel can be fitted except the 10ga and 12ga slug.
If you want to buy a used barrel, just post a want to buy in the classifieds, buying/selling/trading is not allowed in discussion forums. See the barrel fitting info in the FAQs to learn about fitting a second hand barrel to your frame.
Tim