I don't distinguish between new releases and backlist.
Being fresh produce doesn't make a new book any better nor does being old make one any worse.
A read is a read is a read.
If I haven't read it, it's new.
If I've read it, it's price will be a function of my likelihood of rereading.
On the flip side, few if any books are worth more than $10 of my money. They exist but it's a matter of one every few years. That line only dates to 2010 but it's hardened since then. Concrete solid by now. It doesn't kill me to skip pricey books.
My pricing band is essentially $5 +/- $5.
Not a normal distribution, though. My median buy is probably around $3.50.