I believe dwarf hamsters would do fine in an 8". Syrians need a minimum of 11". If you plan on getting a Syrian sometime, the 11" would work. I think a dwarf would be fine in an 11".
I see you are in the US. Where will you buy it? I got mine at
Sugar glider food, Sugar glider cage and Hedgehog food I think they had the best price at the time, although they only come in green and black.