While our local grocers carry lamb / mutton occasionally, I am fortunate to have a direct-from-farm seller at our local farmer's market, who runs a little less pricy on better (cleaner?) cuts than the stores tend to sell. I grew up thinking farmer's markets were just eggs, produce, and crafters, but this one has direct sellers for mutton, beef, and sometimes exotics like bison or ostrich.

Still. lamb/mutton in the States tends to be expensive comparatively, as most places I've lived, if there's sheep raising, it's for the wool.