'Storage Wars' Star -- I Need BIG MONEY or I'm Off the Show!!

"Storage Wars" star Dave Hester -- the "YUUUP" guy -- tells TMZ he's ready and willing to walk away from the biggest A&E reality show ever ... if the network doesn't up their "unjust" contract offer.

Hester was out in L.A. this weekend ... sporting a hat with his signature catchphrase on it ... when he told our photog he hasn't locked up a deal to return to the show next season.

The reality star explained, "Right now I'm in negotiations with A&E and I would just hope they would get away from their unjust contract negotiations ... the ball is really in their court."

He adds, "I don't know what their plans are ... but I would like to be on the show. Maybe 'Storage Wars' without Dave Hester??"

And to make matters worse ... Hester says he wasn't even invited to A&E's Christmas party.