Eminem Blows Roof Off NY Concert But For How Much???

8/8/2013 9:42 AM PDT

Eminem Blows the Roof Off NYC Concert -- But For How Much?

-- now a notorious recluse who RARELY performs -- rocked the house in NYC last night ... and we got video ... but the real question: how much do you pay Slim Shady to drag him out of hiding?

Eminem took the stage at Pier 36 for G-Shock's 30th Anniversary concert -- yeah, the watch company -- and he performed all his hits, including "The Way I Am" and "Lose Yourself." It was awesome.

But seriously, the guy never shows his face anymore -- especially on stage -- so either he got paid a BUTTLOAD of cash ... or G-Shock's contract negotiation skills are incredible.

FYI, Eminem performed for G-Shock last year too at Hammerstein Ballroom. The rapper has a deal with the company -- he even just unveiled its Detroit-themed "Eminem" watch -- and it's obviously worth a ton of money. But how much??? HOW MUCH??????