I bought a new kindle last year to replace an old paper white.
If you can wait for Black Friday there were discounts last year - I bought a 16gb (which seems plenty) with adverts (which are no trouble, you just see one page as you switch it on, nothing while you are reading) and with trade in it cost £95.
I’m really happy with it, like you I read a lot during the night and the new dark mode is even less obtrusive. And the battery lasts for ages.