Floyd Mayweather just went on an INSANE shopping spree with the bank he made from his Conor McGregor fight ... droppin' around a QUARTER MIL on purses!

We got Mayweather leaving Luxury Exchange in Beverly Hills after TBE binged on Hermes Birkin bags ... buying up a crazy expensive 4-pack.

The breakdown, courtesy of their online store:

-1 limited edition white crocodile ($125k!!)
-1 black crocodile (at least $35k)
-1 red crocodile (at least $35k)
-1 ostrich (at least $35k)

Not sure if Floyd got the Birkins for the hot chick he rolled out with -- he's rumored to be dating reality star Abigail Clarke, FYI -- but either way ... he clearly ain't trippin' on a tiny fraction of his $300 mil.