I would avoid the cheap $15 Flea Market Knockoff Throwaway Junk. There plenty of knives out there from great companies at affordable prices. The thing you need to realize is that you're not just paying for the name. With things like clothes and computers, you're pretty much just paying for the name. Take that brand name off the front of the shirt and you're left with the same exact shirt that you get at WalMart for $6. However when dealing with a reputable knife company, you get their guarantee that this thing meets a high standard and will last you pretty much forever, and if it doesn't they'll fix it. You don't get that same quality or service with knockoff brands or the junk you buy from a bucket at the hardware store.
As was already mentioned, Case makes great knives, I think the Sod Buster is about $10 and slip joints are great to start out with. Mora makes a great fixed blade, Opinel makes a great pocket knife, but they're not for everyone. If you really need a lock, Buck Knives make an entire selection of budget knives that are awesome. If you don't see anything you like there, you cant take a look at Kershaw, Kabar, Boker; all of which have knives for people on a budget. Gerber's kind of hit or miss ranging from pretty good to pretty bad, they're not a terrible brand, despite what most people say, their stuff just isn't exactly high end.
Just to give you an idea of what's out there. All of these cost less than $20 and regularly make it into my pocket.
View attachment 335055
Look around a bit, there's a lot of options out there from good companies. Also, avoid taking Youtube reviewers too seriously, just because they have a camera and some free time, that doesn't make them experts. Find one that you really like.