Looking to replace my dads 870 barrel with a new one. He bought it 25 years ago from "a friend" but it only has a 14 in barrel. Looking to make it a useful hunting shotgun. What do I have to do to get this replaced? Price?
Barrels for 870 shotguns are readily available at large outlet stores such as Cabelas and probably by order at your LGS. They can be found at a number of on-line retailers like Bud's too. All that is necessary is deciding what type of hunting you want to do, what you want and then finding it at a price you're comfortable with.
They are available all the way from cylinder bore SD barrels to 30" vent ribs with RemChokes. One thing you probably should do though, is check your receiver and get a barrel that matches the mechanism. In other words - don't get a +3 inch magnum capable barrel if your receiver is designed for 2 and 3/4 loads.
I get most of my parts from Midway USA. They have several Remington 870 barrels from 181/2" for home defense to rifle sighted slug barrels to barrels with screw in chokes. Prices from just over $100 to over $300. I have 2 870's in 12 gauge not many guns more versatile or reliable, unless it is a Ruger P89 or Security Six.