Here’s a few things you should answer for yourself before you start looking:

• What kind of tires do you want? Skinny street, wide street, off-road, fat ones, etc.
• Do you want it to fold in half for better storage in an apartment, at work, or in your small car?
• Do you want good full coverage fenders that are close to the wheels for riding in the rain without it ending up all over your back and legs?
• How far do you want to be able to travel round trip?
• Are there any other important features you want?
• What’s your price range? (I know you already said not too expensive.)

I personally bought a folding bike from https://www.greenbikeusa.com/ because they are cheap, they can fold, they have full coverage fenders, they come with a rack, and I was able to attach a basket. it’s a cheap Chinese bike that arrives folded up in a box partially disassembled and the shifter needed calibrating so as long as you are OK with that it’s been a great value.