12 month old sleep n plays!!! please help?

My son is 6 mths old and is starting to grow out of his clothes which are sized for 9mths. I need to start getting him 9 to 12 or 12 mths. When I looked at sears I noticed they have 12 mth sleepers in the toddler section which were also double the price of 9mth sleepers. Does anyone know any other stores that sell 12 mths clothes and sleepers that aarent expensive?