The Macbook Neo is $600, great, will likely last a long time, and you can split the payment over a year or two years with no interest at a lot of places if you think a credit card is okay. You might be able to grab a used M1 Macbook Air for less than $600, but not a whole lot less.

For Windows, used ThinkPads are good buys even when they're old and cheap. Note that when you search for ThinkPads you'll sometimes get other Lenovo brands that aren't as good, stick to ThinkPads. Something like this is probably needs suiting. This is probably what you want to go with, the main reason to go with the Macbook would be some extra battery life, longevity, not having to deal with windows.

Let me know if you have and qs and good luck.