I might be getting a Dwarf that has maxed out at 10'...What size cage should I house her in? I was told I could get by in a 5' cage, but 6' is optimal and a 4' cage would be pushing the small limits?

For the SD's would a 5' cage also work? I'm really trying to save some $$ and avoid the cost of a 6' cage(s)...

Sorry for the repetitive question...I couldn't find a good answer using the search...