WhichOneHowMuch Toolbar Rated 4 out of 5 stars

I've recently downloaded this (and it's the first time I've used an add-on) and it works as it says. Lots of money to be saved I reckon.

This review is for a previous version of the add-on (1.1.653.1-signed.1-signed).  This user has other reviews of this add-on.