I'm just starting in this too. I have a 1.3 group right now. I went with the DIY tub method commonly used on here for those that don't/can't do a rack setup yet. I followed this one here http://www.metalmonkeyexotics.com/blog/?page_id=982. I have one built right now and two more tubs the same size waiting for me to build tomorrow. One tub will be a grow out tub and the other I haven't completely decided yet. It'll probably end up being another harem tub when I get a female keeper from my breedings. I'll see what I need as I go I guess. My thought is everyone is different so what works for someone else might not work for me. Only way to know is to hit that point on my own. My space is a small open closet/cubby area is my room of our apartment so I've gotta work in the space I have available.
I read through about 75% of all the threads in the rat feeder section and still am learning as I go. They seem like pretty easy keepers and the one female I have that is overly friendly and begging for my attention all the time makes it so worth it. She's got a home for life.