Thank you for responding. I'm going back and forth on this. I know I could do it, like you said—buy a 24mm socket, turn the motor, wedge the belt off the bottom or middle pulley (which is rounded), replace the alternator, and get the belt back on following a video guide. It would probably take me about 3 hours.
The pain, I know the dealer will charge around $1,000, with about $350 of that being for parts. Ugh. This Tahoe has been a bit unreliable for me. I have a landscaping crew assembling with 20 large rolls of grass to install today so I think I'll move onto the next Saturday chore.