Former "America's Next Top Model" contestant Don Benjamin hit up an art supply store in the middle of an afternoon, and ended up getting jacked for $3,000 ... at gunpoint.
A rep for Benjamin -- who was on Cycle 20 of the show in 2013 -- tells TMZ he was walking into a store in downtown L.A. on Wednesday around 3:00 PM ... when the attacker put a gun to his head.
Benjamin immediately forked over 3 grand in cash and the gunman bolted with another guy in their getaway car. He reported the incident to police, but was unable to give them a suspect description.
Law enforcement sources tell TMZ they are investigating, but so far ... no arrests.