http://www.bit-tech.net/hardware/cases/ You can pick up cheap cases that are plenty roomy in size, but dont expect too many options for cases with any/good fans or great cable management- many lower-end cases like this are cheap for a reason; a good case that is used would be your best bet for getting a quality item. Hence, check out the reviews and then go on a rummage around the tubes of the interweb...
The Antec 100 is just under £40 at Scan at the mo. I don't think you can go wrong for that money, have a read through the BT review here. Seems a good buy for the money, rear and top fans included (AFAIK) and room for 3 more 120mms. Hell, it's not the best but I'd plump for it if I needed a case for £50.
Yep i have built in lots of Z9's very easy to build a tidy system in, plus the budget Fractal range are good for the money, better in real life then the pictures do them justice. The big one is the Core 3000: http://www.quietpc.com/gb-en-gbp/products/pc-cases/fd-core-3000 Or an Antce 300, as i think the one hundreds look too cheap.
