TLC, has you ballparked, I generally tell you about the knife. The 313 shape of knife is a two blade, opposite end, skinner with one spey blade. Knives of this design were favored by trappers for removing and preparing small pelts. Hence the name "Muskrat". In fact this knife was and is still favored by muskrat trappers especially in the midwest and Mississippi valley.
Production started in 1972 and ended in 1998. "The 313 Muskrat was manufactored by Camillus for Buck and was added to the line in 1972 along with the 311,315 and 317." (Oden, Knife World, p.28, Jan.2000). It's usually found in only three variations, blade tang stamped BUCK,313,Made in USA; blade tang stamped BUCK,313,USA with one nail nic groove ground in scale on front and BUCK, 313,USA with a nic groove ground in both scales.Not considered extremely rare they are still sought after by trappers for everyday use. Other manufactors made similar models.
Price varies greatly by quality. Buck currently offers "like" models made in China, under diffferent model numbers with several scale types. ..... 300$s