I got mine from my Chevy dealer. Gave Sara the part #, and she made a quick search nationwide, made a phone call, and 2 days later I had my antenna. I paid list price, for the exceptional service.
Your parts guy doesn't know WHERE or HOW or is unwilling to do a nationwide search. Most don't. My Pontiac parts guy (they are now out of business) couldn't find one. I went directly across the street, and like I said, had it in 2 days.