Even if I had $6.10 (or $1.25 or $8.50) to spare, where would I send it?

How about:

Golden State Warriors
Attn: Gilbert Arenas
1011 Broadway
Oakland, CA 94607-4019

The Warriors' web site FAQ reads:

"We receive several hundred pieces of fan mail every month for our players and coaches, which are forwarded directly to them."

Be sure to mark your envelope "Gil Don't Go!" so they know you care....