PHP store solution that allows for multiple unique storefronts per

i'm looking for an online store i can buy that will allow multiple
storefronts per category, each having their own unique design but
culling from the same database, does anybody have any suggestions?

X-Cart does not naturally do this and you have to shell out a bunch of
$$ for add-ons etc to make it work as far as I know...

any suggestions would be great.