That is akin to asking how much a new engine is. Barrels come in a wide range of styles, uniformity, cost and quality. Most who seek a custom barrel are interested in some aspect of the barrel that is not available from the factory. It might have to do with contour, weight, or length, a particular rifling style or a nonstandard rate of twist. The buyer may simply want an inexpensive factory equivalent barrel due to physical damage to the original, or he might be unsatisfied with the level of accuracy possible with his factory barrel and opt for a match quality barrel. A factory equivalent barrel can often be selected from a pile in the corner of many gunsmith's shops, and might cost anywhere from $60 to $100. A top rate match barrel over 28" in length could $1000 or more, plus the cost of installation and chambering, but more often is half that. As with all things custom, every change from standard has a price attached to it.