Quoted By:
There's a lot of options, can get confusing at times, what size you need, what options you want, ect ect... but let's just keep it simple.
Check out Teton sports on Amazon. They have really nice, well made packs for under $100.
Now you'll want a pack that you can use for 1 night, and possibly a few more. I'd reccomend the Teton Sports Hiker 3700. It's well under $100, will fit everything you need, looks cool, and is well made.
If you want smaller, they have all sizes, and several larger sizes too.
They're a decent company too, not just a knockoff brand. They have youtube videos of all their products if you want to check that out.
Personally I went with a High Sierra pack. Also a good option. I have a Sentinel 65L (they have a similar 55L pack too). I went with that because it was on sale... otherwise I would have got the Teton (my brother has the hiker 3700). Both are nice for under $100. The high sierra seems well made, and holds everything I need and then some.
Pic related, my high sierra pack.