I use some cheap discs for my computer(8 for 1 pound from poundland)and some JVC audio discs for music(2 for a pound from poundland).Don`t think you have to spend loads on discs,I`ve always used these and they work fine,you can record loads of stuff for next to nothing.
In addition to my fisrt reply: firstly you could also check out http://www.cdfreaks.com/reviews/CD-R-media-quality for some more info/opinions on the quality of certain cd & DVD media. I can't say how trustworthy these comments are, but a least they provided us with a method to test the quality of cd-rs ourselves. Check out CDcheck, EAC and Feurio for this purpose.Secondly there are some hifi stereo magazines that test the quality of cd-rs. Check out the best buy section at the back of these mags and I'm sure you'll find some suggestions that'll put you in the right direction.