Yeah, but £50 to try your hand at mixing on a whim is ridiculous. Audacity is fathomable, and if you're anything like me arcane bits of knowledge about, for instance, how to get a useable sound out of Gverb will bubble up in the cortex for years to come.
Exactly -- for the kind of thing the OP is talking about, where it's pasting together a few sections, a bit of crossfading and *possibly* some tempo shifts, Audacity is easy enough to use -- Tracks->Add new, Edit->Copy, Edit->Paste, Effect->Fade In, Effect->Fade Out and Effect->Change Tempo are all the commands you need to know.
Audacity is also a much, much faster-running piece of software than any other audio software I've used, so if you're running it on a home machine that hasn't been especially built for audio work it'll be much more responsive than other software.