We just got the 4x6 coop from Cedar Grove Products this weekend and love it.
It weighs a ton and we had to help the guy who delivered it roll it along pvc pipes across the yard. Once it was in place we couldn't even begin to budge it. I think putting strong wheels on it might be a good idea should you want to shift or relocate the coop at a later date.
Our chicks - for the record - went to bed in the new coop on their own tonight. I am one proud chick mama!