The options of whom to have sleeve a gun over here are somewhat limited and hence pricey. If the gun is valuable enough to justify the investment it can be done. Often it is easier to just find a second set of "donor" barrels and fit them to a gun as a means to bring new life to a worn out gun.
With 20-25,000 guns, even in small bores to draw from, an extra set of barrels can often be found. Some of us buy all the good condition double barrels we come across for future use. I have used them to restore Lefevers, Bakers, Foxes and others. Much poorer luck finding Parkers and Smiths that easy fits but you never know.
