This is the PC that I have built as of right now.
For the case, I need something that is fairly quiet, but I can deal with a little bit of noise. Am I going overkill on the case for a $500-$600 PC?
Is there any Ram with equal performance to the Corsair Vengeance 8GB that isn't so expensive?
Is that power supply good enough?
Also, if you have any other suggestions, that would be great :D
Looks like a pretty solid build. All ram is pretty expensive right now with the shortage.
The case is your preference. It's what you're going to be looking at every time you look at the thing, so I think it's important to get what you want and what will suit your needs, within reason. That's a nice case and I see no problem using it for a build in this price range.
So many awesome cases in that price range but if it's noise you're worried about you should consider getting some fans. Even though the new fans by Corsair are quite better than the previous ones. Silverstone fans are quite good too, should you get a case by either of the two. Maybe see if the fans the cases come in are PWM fans, so you can control their speed through BIOS.
If you're planning to upgrade the ram within a couple months, I would stay with that single stick. Dual channel still has better performance, though.
760K is cheaper ATM.