Hmm. Back when I played around with this stuff I had tried out Prosoniq Time Factory which ain't cheap at $449. But they now appear to have a stripped-down version, EZ Time Stretch that will change time but not pitch for $179 (Time Factory would let you do both time and pitch if you wanted.) Back then there was a demo available for Time Factory, but no demos of either product seem to be available (though they do have sound samples to demo Time Factory.)

Maybe you should sneak over to KazAA or the like and, copyright morals permitting, give EZ Time Stretch a shot, and buy it if you like what it does.

Edit: Looking closer at the page, it appears they no longer sell EZ Time Stretch, so it sounds like the P2P route is the only way for that partiuclar program.