I have used a tascam (about $159)to slow down, change keys, and maybe best of all, loop segments to play a bazillion times over.
You just pop in a cd and go. It takes a bit of fussing with it to figure it out, but not bad.
I haven't used mine in quite a long time, but I used to.
You could check on ebay. Zzounds.com is a good co. to check out for this type of stuff, and I have found that they have good reviews on lots of gear.

Kirk J

I usually use Sound Studio. Pitch and speed are tied together, which isn't what you always want. There is a 'fader' you can slide to zone in on the pitch; Getting that Bb flat tune to match you C accordion. If you change pitch by 100%, you'll get half the speed and one octave lower, cool for trying to figure out all those tough little licks.
Steve