On July 15, Yankee Stadium, which opened its gates in 1923, will host its last Major League Baseball All-Star Game. Come October, it and its crosstown counterpart, the New York Mets’ Shea Stadium, will be abandoned in favor of the new Yankee Stadium and Citi Field, replete with skyboxes, club seating, and other money­makers. But the doomed stadiums promise revenue streams from their memorabilia, destined to be auctioned sometime after this season’s last pitch. The teams are negotiating with New York City, which owns both stadiums, to salvage coveted collectibles: seats, lockers, signs, even clubhouse urinals.

No agreement has been made on­ how the city, teams, and as-yet-­unnamed auction houses will split the proceeds, but the auctions are likely to be lucrative. Last year, the city of Detroit grossed close to $2.3 million by auctioning pieces of Tiger Stadium, and the St. Louis Cardinals raked in more than $5.4 million for 20,000 seats and other items from the old Busch Stadium.

New York prices are, of course, a whole different ball game. Pairs of seats from Shea could command $500 and pairs from Yankee Stadium $1,000, says Brandon Steiner, C.E.O. of Steiner Sports Marketing, a memorabilia distributor. And with all the seats expected to sell, auctions could earn $28.7 million for the Yankees and $13.9 million for the Mets (minus cuts for the city and auctioneers).

Bids on lockers used by Derek Jeter, Alex Rodriguez, Reggie Jackson, and Thurman Munson are likely to break the $21,503 record price for Albert Pujols’ old stall at Busch. (If a Yankee wants to keep his current locker, ­he’ll probably have to bid on it.) And true obsessives might be eyeing far bigger items. The oversize exhaust pipe ­at Yankee Stadium that’s painted ­as Babe Ruth’s Louisville Slugger? Shea’s big apple, which rises from a giant top hat after every Mets home run? Priceless.