There are cheaper programs, but in the end they are cheaper programs and do not have the functionality that Cool Edit (and now Adobe) has. Cool Edit was developed as an alternative to professional programs like ProTools, and in fact Cool Edit has been adopted by others. I guess it depends on what your needs are.   

Another program that people swear by is SoundForge, but I've found it to be a bit cumbersome and not as flexible as Cool Edit - although I do not have that much experience with SoundForge.

If you had Cool Edit, I believe you can can an update cheaper (I'm not sure how much a "quid" is.)