Cheech Marin -- $55,000 in Guitars ... Up in Smoke

Cheech Marin better hope guitar chop shops ain't a thing -- he just had 4 extremely unique ones swiped from a private warehouse, and he's begging the thieves to return them.

Cheech owns a bunch of rare guitars -- many of them are actually works of art -- and TMZ has learned 4 of those axes were lifted Monday in Los Angeles. Estimated value of the stolen instruments ... $55 GRAND!

We're told the guitars are one-of-a-kind, so they really can't be replaced. Cheech is putting word out to local artists in case anyone spots his 6-string babies.

Note to the thieves: Don't smoke the guitars. They're not made of hemp.