>>105769436
I'm down

>What's the going price at each $10?

(less than...)
$10 r5 340x
$20 r5 430
$30 quadro k1200
$40 rx 460 (4gb)
$50
$60
$70
>$80 - how about the r9 390x?
I'd recommend rx 580, as driver support is more up to date and are easier to find in the used market. r9 390x is roughly 4-7% better.
https://technical.city/en/video/Radeon-RX-580-vs-Radeon-R9-390X
$90
$100 rx 5600 xt

These are cards that I've have/had and experienced in these price ranges