Obviously the bigger the range the better your chances but to some extent it's a matter of luck anyway.
In my experience, even within the same size and brand the comfort level can change with each helmet. When I was riding I generally had better luck with the AVGs for my head shape - (don't know what brand would best suit your rude looking <box>head
)
I generally try put the helmet in a price/value bracket - i.e am not convinced that a $900 helmet is 3x better than a $300 helmet - but would not consider a $60 helmet.
You may need to make time for a couple of stops on the way
Good luck with the search -
LoBelly