I think i am getting another hamster.i have questions?

i'm thinking of getting two hamsters.i had one but it died about 3 days ago and i want another hamster.i am thinking of getting robovoroski hamsters this time.(i had a golden hamster).i still have my old hamsters cage and the cage is new.for the robovoroski hamsters it will be plenty of room.(its a 24"Lx13"Wx14"H cage)should i get 2 females or 2 males.or 3 females or 3 males.i do not want to get a female and a male because then i would have a problem.also whats the average cost of them and where could i buy them?i live in burbank,california.should i get them from millenium pets(if you know that place)?