I've not heard the term "supersump" before. If you are referring to a 1/3 hp sump pump, then my guess is that he is referring to a Zoeller M-53. This is one of the most common models installed by professionals and is generally a very good unit. The big box stores do not sell Zoeller, but many smaller hardware stores do and you can also call a plumbing supply house....they will often sell to consumers.
A Zoeller M-53 is going around $130 or so in my area.