what do you mean by squeal? Pinch Harmonics will do that, and no pedal required!

Only other thing I can think of fitting the bill would be a whammy pedal / octaver or similar....

Maybe I don't understand.... got that Monday feeling really bad.... :(

As a general observation, I buy most of my pedals from ebay - cheapy cheaps.... I got a keeley modded DS1 from a seller in the states delivered to me in the UK for £55...