EXCLUSIVE

Kanye West was a forgery victim and the cost is huge ... nearly $1 MILLION ... sources tell TMZ.

Sources close to the situation tell TMZ, a guy Ye knew secretly contacted Philipp Plein, who is staging a big New York Fashion Week event this coming Monday. The guy misrepresented himself to Plein as Kanye's rep and began negotiations for Kanye to perform ... at a STEEP price.

Plein apparently fell for it hook, line and sinker, and they made a deal wherein Kanye would supposedly pocket 7 figures and, in return, he would perform at the NYFW show.

It gets worse. We're told the guy forged Kanye's name on the contract and then had a $900,000 advance wired to an account ... which the guy promptly cleaned out.

Kanye's not performing at the show, and Plein is now out a pretty penny.

As for the guy who committed the alleged fraud ... we're told he's a former friend and associate of G.O.O.D. Music.