I don't know if this is the same con cheapo jobby, but a mate bought a similiar sounding device from ebay for his corrola a year or two back.
He took it to bits - it was a single high power resistor that connected across some wires near the air filter and i assume somehow fooled the ecu into thinking the cars air intake was at a different temp from actual temp, so it added more fuel for a richer mix (don't the exact connection details - it was a bit sketchy - i guess some air temp sensor or such like). That was the general consesus from what i remember. Might not be the same thing, but?
He said he could feel a difference in certain conditions, but read up on it on the web and was advised to remove it. Think they might have called it a 'power chip' or sumthin like that - can't remember, i'll send the guy a mail and find out. It was around £20.
Don't know if the 'ignition advance unit' is a nice name for a resistor, or if this is a similiar ploy with a different device and connection, or it might even be something different that works, but i have a cynical mind.
As has been said already - anything that cheap, supplied in bulk on ebay, for most models/platforms... gonny no.
Anyone heard from someone who's bought one of these actual units?