TMZ Sports talked to David Kohler from SCP Auctions -- one of the industry leaders in sports memorabilia -- about the value of basically everything but the record-setting baseball.

"Certainly the bat, the tool, the trade that he used yesterday to hit this historical milestone home run. That bat's worth a lot of money and the uniform he wore. Those are Aaron Judge's basically right, so I'm sure he's keeping those, but again if we had those at auction, in our firm, SCP Auctions, that's gonna probably bring, for a pair, probably a million dollars."

"Of course, his cleats that he wore, his batting helmet of course -- all those things are gonna bring big bucks for this very historical moment."

And, Kohler says if Aaron were to inscribe any of the items, they'd be worth even more!

As for the baseball, it's still the most valuable item from the historic game ... and worth upwards of $2 million.

"This baseball's worth a lot of bucks! Our estimate actually, with everything that's gone on in the last week or two leading up to the last game yesterday, our estimate is over $2 million for this baseball!"

FYI, Kohler's company has auctioned some of the most important balls in sports history ... including Barry Bonds' 500th, 755th, 756th and 762nd HR ball, as well as Alex Rodriguez and Mark McGwire's 500th HR baseball.

And, they'd like to add Judge's 62nd ball to the impressive list.

"We haven't talked to him personally yet, but we reached out to him," Kohler says, adding the situation is very much like a "lottery ticket landing in your lap."