Carmelo Anthony -- SNEAKER ENVY ... At Wild 30th Bday Party

Carmelo Anthony's 30th birthday party was INSANE this weekend -- with surprise performances ... super expensive champagne ... and a RARE pair of Nikes that's driving the shoe community NUTS.

It all went down at the NoMad Hotel in NYC -- where huge stars like Nas, Swizz Beatz and Busta Rhymes all performed for Anthony and his famous friends.

The guest list was A-list all the way -- Alicia Keys, Chris Rock, Ciara, Jessica Stam and Tyson Beckford.

At one point, Chris Paul called in ... he was put on speaker phone and reportedly said, "We have a new owner. Sign with the Clippers!"

But EVERYONE in the party was talking about Carmelo's shoes -- a pair of Jordan 11 All Reds ... shoes that no one can buy and may have been custom made just for C.M.

It's like seeing a mermaid riding on a unicorn making out with Kate Upton.

Even Nas tweeted about it ... "@carmeloanthony had the crazy feets on last night. I need these!!!!"

Good luck.