Just wait on the CPU/mobo/GPU.
It's way too close to a big update on all three fronts unless you're going with an AMD CPU/mobo combination and prices on those may well end up dipping a bit once the i5 CPU/P55 1156 socket mobos become available.
Another factor to consider with the i5 is that the P55 mobos will cost significantly less (plenty in the $100-200 price range) than the i7 X58 mobos, which are technically still "enthusiast" boards even though decent X58 mobos are currently available for under $200.
DX11 VGA cards are right around the corner. Even if you don't spend a premium buying one (you shouldn't if on a tight budget), their availability guarantees everything else drops down a bit in price.
If you buy a case with a PSU pre-installed, it's really not any more plug and play than if you bought them separately. It's literally 4 screws to mount a PSU into a case. Cable management is what gets a bit trickier once all components start going into the case (keeping everything tied down, clean and clutter free to optimize air flow).
The downside is that the cheap PSU/case combos often have no-name brand PSUs. Generally, the PSU is not the best component to skimp out on (a common beginner's mistake). You're better off buying a quality PSU with a history of reliability for a bit more.







