Blade should be marked "US" on one side with a date - from 1894 to 1903 on the other. Most collectors prefer to have the bayonet complete with scabbard. Loose bayonets sell, but not as quickly.

Prices range from perhaps $35 for a very rough one (no scabbard, rusty, nicked, chipped grips, excessively sharpened, etc.) to as much as $275+ for a pristine example, with scabbard, EVERYTHING perfect, NO signs of ever having been sharpened, etc.

Most fall somewhere in between.