several cheap phones from Motorola, Sagem, Samsung, etc. (I couldn’t afford a Nokia 3310)
some no-name feature phone
some Chinese 60€ smartphone
Samsung Galaxy J5 (used)
Samsung Galaxy J2 (got it for free)
Gigaset GX290
Unihertz Atom
I’ve never spent more than 150€ on a phone. If you debloat them and use open source apps, you really don’t need many “features” or much CPU-power/memory/storage.
And I don’t think I’ve ever a used a different browser than Fennec, cause that’s what pops up if you search for Firefox on F-Droid.