i have two cases (both were a little more than 15 dollars).
one is a turquoise silicon case from Pink.
the other is a rose gold hard case by spigen. this one is actually very protective. i've dropped my phone quite a few times in this case, and the case and phone are still completely fine.
I have a hybrid case that I bought off of ebay for about $6. It's part soft shell part hard shell so basically I get good enough protection, those are the only kinds of cases I buy for my phones. As for screen protectors, I just had the way they make the screen look but I do have one on my 3ds.
i have a hard plastic case that covers both sides of my phone and has a built-in screen protector and it came with a little jelly case to go over top of the hard plastic one. i'm really shaky with my hands and i'm always dropping things or losing them but i've never cracked my screen or damaged my phone with the case i have now because it's so well protected. i've even dropped my phone down a flight of metal stairs at my school and the screen didnt break lol. i think it was around $20 but it's well made so whatever lmao.