Google xcm black knight, it's a 3rd party black case for the 360, often on eBay for £20, I have a black wii case of theirs and it's good quality, you'll struggle to find a genuine elite case I think (eBay would be the bes place to look though).
The 360 comes apart reasonably easy, would take you no more than 20 minutes and there's plenty of YouTube guides, unlike the wii which took me 4 stressful hours to do! It helps if you have a 360 case opening tool (comes with the black night I think) though you can do it without.
You could just trade your premium for a new elite?! Some cracking deals around at the moment so by the time you sell or trade the games that come free with ityou shouldn't have to pay more than £30-40 to trade up, plus new warranty and hopefully a new jasper model 360 which'll be quieter and more reliable!
Google xcm black knight, it's a 3rd party black case for the 360, often on eBay for £20, I have a black wii case of theirs and it's good quality, you'll struggle to find a genuine elite case I think (eBay would be the bes place to look though).
I bought the XCM Smoke case with the white led air tunnel and it looks awesome, the XCM cases come with an opening tool as well which makes opening the case easier (but its still pretty easy to open it without the tool, theres quite a few tutorials on youtube). Beware, some of the internal case mods are for the older/newer console models, make sure that any mod you buy is compatable with your model 360 (however all the cases will be fine for all models).
EDIT:
By model I mean jasper, falcon etc. The internals and layout of a jasper and falcon are quite different, so some of the extra fans you can buy for the 360 will only fit the jasper OR the falcon not both.