It's a much smaller scale of miniatures than the normal GW line. It can be found under several names, but the most common is Epic 40K and currently as Epic: Armageddon. I am not sure which exact miniatures would have came with the Space Marine game though.

GW still sells the minis on their website for Space Marines, Eldar, Chaos, Orks, and Imperial Guard.

http://store.us.games-workshop.com/storefront/store.us?do=Li...

"epic mini set" doesn't ring a bell, but in the early days you had boxed set, for which you can find pictures in the gallery, like this one:



or 2nd edition box sets, like this one:




not sure about the Epic 40k era,

and then after that it's the Epic Armageddon era, whith box sets still available,
http://www.games-workshop.com/gws/content/article.jsp?catego...
of course some mini's were always available in blister packs too.

cheers,