Yeah.....uh, $400 is a lot. Esp if you just need a 'script for Ambien. That's just D-U-M-B they would charge that. No, you're not being overly sensitive.

Can she maybe refer you to someone who accepts insurance? Or maybe someone who isn't so off-the-charts expensive?

There is no shame in not having the money to pay for something you cannot afford, especially if that certain something is overpriced to begin with, ESPECIALLY if she knows you don't have money coming out the wazoo. But then again, if she DID in fact forget that point, I would not hesitate to kindly offer her a gentle reminder.