New and used Henry Big Boy .357 Magnums typically cost between $500 and $2000, as of 2015. The MSRP is $899 for the standard model and $1,995 for the Deluxe II model.
The gun auction website GunBroker.com regularly has factory new and used listings for Big Boy rifles. A used Big Boy can sell for as low as $500, and Deluxe and engraved models can sell for over $1800. Cabela's sporting goods website sells the standard edition Henry Big Boy for $799. This model comes with an American walnut stock and brass butt plate. It is available in .44, .357 and .45 Long Colt calibers.