Here’s what I would do in your shoes, if $500 wasn’t acceptable...
Go to a dealer, CarMax, Toyota dealer.. used car lot.. anywhere.. — ask them to BUY your car. See what number they give you.
Autotrader, KBB, NADA, even BlackBook..they can’t see your car.. they can’t know how much it would cost to fix everything- which is unlikely that anyone will.. and they don’t know the price it will get wholesale. They’re consumer estimate guides, but they don’t actually buy cars.. most importantly- once a car is older with problems, the numbers aren’t even a good consumer estimate, they’re more misleading than anything at that point.
Or- take photos and post it online to sell it yourself.
You’re going to drive yourself crazy over a minuscule amount of money/headache/time wasted.. you know the car you want, you like the price of it.. So just buy it! Deal with your other car separately.
I think you would feel a lot better.