I'm really not that impressed with the cooling of the CM 690 II, seeing that my 2x GTX 460's + i7 940 run pretty hot (well above 60'C), and I've installed additional fans too.
The other issue that you'll have with the 690 II is that the removable (tool less) trays are from plastic, so the hard drives can't transfer some of their heat to the case either.
There aren't really any decent, but cheap cases around, otherwise we would've suggested other brands than Coolermaster

... which is why I've basically just suggested Coolermaster Elite 430, 690 II cases before.
If you want a really big case, then look at something like the Aerocool PredatorX, which retails for about R1100, but it is quite ugly IMO.