Most online sites do 100 big blinds is the max, while UB/AP has 200 big blinds. Also on pokerstars
they have varying buyins at the same blind level (i.e. a 50bb min table opposed to a regular table), usually you don't see the 50bb min until you atleast reach a decent limit.
Casinos usually go 20bb min and 50bb max, but as you get higher in limits the max buy-in grows. For example where I deal the 1/2 game is $100 max and the 2/5 is $500 max, granted we also do offer 1/2 $200 as a seperate table with $100 min.