Kevin Garnett -- Drops More than $20,000 ... On 1,000 Ticket Giveaway

Kevin Garnett didn't get an employee discount when he bought 1,000 tickets to give away to fans for tonight's Timberwolves game ... dropping more than $20k of his own money, TMZ Sports has learned.

After fans came out in force to attend KG's first game back in Minn. last week, the NBA legend decided to give back ... by hooking up 500 fans with a pair of tix for tonight's game.

Smelled like a team-engineered publicity stunt ... but the V.P. of Communications for the T-Wolves assures us that Kev bought the tickets HIMSELF and paid FULL PRICE for all of 'em.

The rep wouldn't say exactly how much KG spent ... but the cheapest seats go for $21-a-pop.

$21 x 1,000 = $21,000. Not cheap.

KG's career earnings? $315,000,000+ ... so, he can afford it.