(this is a post that I wrote for another very similar thread)
The coolermaster haf 922 is probably one the best mid-range cases you can get for under $100.
Some of it's features include:
five 5.25" external drive bays
transparent side panel window
two enormous 200mm fans (one in the front and one on the top) as well as a 120mm rear fan
tool-free installation of drives
Ton's of room to fit the largest video cards (and liquid cooling)
With two usb 2.0 ports, audio, an e-sata (yes there is one). This is definetly good enough as USB 3.0 still isn't mainstream. Also if you invest in a decent motherboard you can have the usb 3.0 ports that you are looking for. My advice is don't let the front I/O ports be your deciding factor. This case is very spacious, well built, and even looks pretty good. This case is currently going for $90 on newegg and that price drops 10 bucks with a rebate.
or you could get the haf 922 advanced with usb 3.0