Replacing batteries on a Windows laptop is probably fine for anyone who has some basic repair abilities, with the exception of Macbooks. Since around 2019, they are next to impossible for anyone to replace. You basically have to completely disassemble the entire thing to replace the battery. Not fun.I'm a lot cheaper than these suggestions! For the email and general browsing I do, a $400 HP laptop from Walmart works great. The battery will have to be replaced in a year or so otherwise it's more than adequate.
For your budget you could get two and still be ahead. Totally different deal if you "work" on it, get something more robust but for a bigger screen and keyboard than your phone, easily fits the bill. A 1tb external drive is likely more than you'll ever use and can be moved to your next PC.