Most people can't afford one Bugatti supercar, worth around $2 million -- Floyd Mayweather has THREE.

The boxing champ just showed off his insane car collection -- comprised of some of the most rare and expensive cars in the world.

Here's the checklist with approximate market values ...

Bugatti Veyron -- $2 million
Bugatti Veyron -- $2 million
Bugatti Grand Sport -- $2 million
Ferrari 458 Spider -- $250k
Ferrari 458 Spider -- $250k
Lamborghini Aventador -- $400k
Porsche 911 Turbo S $180k
Ferrari 599 GTB Fiorano -- $300k

Grand total ... $7.3 MILLION.

And unlike Justin Bieber, Mayweather has his own private jet ... and they don't exactly come cheap.

FYI -- Mayweather has reportedly made more than $400 MILLION in his career ... and clearly, he ain't afraid to spend it.