I have a robo dwarf ham, and I made her cage out of a 110qt plastic bin. All you have to do is cut a hole in at least two sides and install mesh over both sides. The mesh needs to be small, 1/4 inch or less for each cube, and I cut mine two inches larger than the hole on all sides (to help prevent escapes) There is a wealth of knowledge on building bin cages on Youtube some personal favs are:Hammy Lux, TheHamsterNinja, and Small pet junkie. I learned to make mine from seeing videos like these. There is also an ikea detof cage as an option, Hammy Lux has some info on hers. Bin cages are like the C&C cage of the hamster world, much better for health, happiness and wellbeing. Plus it's a lot cheaper than finding a cage that is an appropriate size.
I would reccomend a syrian to start, they (in general) are more friendly and easier to handle, they also tend to be a lot slower (my robo is VERY fast and she jumps) so as a new hammie mom, I would reccomend a syrian.