Does CreateSpace charge different amounts for different trim sizes?
Price-wise, there is currently no difference in price for the various trim sizes, and you can verify it directly with the sizes that you are thinking about on their “Buying Copies” tab for their book publishing info page.
The price to ship from CreateSpace is the same no matter the trim size. All that matters there is where you are shipping your books and is based on quantity. Click here for their rate table.