my rec for under 100$ is don't. it doesn't matter how light your use case is, you're just gonna get crap that will die in one year, if it doesn't make you punch it yourself before that. get a barely used old thinkpad if you find one and put linux on it. in general if a laptop's target demo is businesses it'll be a great find on second hand markets because a company has probably bought them en masse and then dumped them due to debt/downsizing and most of them will be healthy. do not get chrome books if it's garbage for elementary schoolkids it'll be garbage for you.
if you just don't have the budget for a new laptop and if your current laptop can be upgraded, put a SSD in it, it's the best way to revive an old laptop. although with the current prices i'm not sure if you can do that under 100$ either.
