It's time for the rest of the story. After chatting with you fine folks and doing some Internet research, I contacted Costco and True Car. And then was flooded with emails, texts and phone calls.
The TC quotes from 3 dealers were okay but none of them were for the exact model/color she wanted, grrr.
Then the first guy who contacted us from the Costco Program (a different and closer dealer than TC) was a total used car salesman. Turns out they didn't have the exact car either and wanted to sell me something other than what we'd requested, which pissed me off. Also, you don't get any pricing in the confirmation email. You have to go to the dealer to get the price. I also received an email from the GM of that dealership saying all the blah x 3 about he hoped everything was wonderful.
At that point, we started the repair the old car vs. buy new discussion again.
Two days later, I got a "How was your experience?" email from Costco. I decided to respond to the GM's email and tell him about my experience before I responded to the survey. I got a call back from a different salesman within 10 minutes. This guy was night and day from the first guy. He listened, found the car, and quoted me a price over the phone. He agreed to have the car transferred to their dealership. We made an appointment for Sunday.
On the appointed day, DH and I met our friend to the Toyota Dealership. She test drove the car and decided she liked it. She put 10% on a rebate CC (the most the dealership would allow), wrote a check for the rest, and traded in her Volvo. We did haggle a bit on the trade in. Their first offer was $1k, but their second offer came in at $1250. Given her circumstances, that was close enough. She also wanted door guards installed, which had to be ordered and paid for separately. The parts came in yesterday and she brought the car back for them to be installed. The service guys tried to charge her $450. The sales guy had quoted her $350. When she politely reminded the service guys that she was buying through the Costco program, the final price dropped to $319. In all, her very well equipped 2017 Camry V6 XLE was a smidge under $30k out the door.
In conclusion, buying through Costco was relatively painless, but you still have to pay attention to the details, and advocate for yourself (or your friend, in this case). It was kinda fun spending someone else's money. Now she can focus on her recovery and enjoying life and her new Camry for at least the next few decades.
Thanks for all of your help!
To jane x: interestingly, a friend of hers purchased a basic 2017 Camry SE for $20k the same week.