Please check The money of "Freak Show" first to see if the item you're looking for is there, because many items cost relatively much more or much less in the 1920s compared to today. But if all else fails, use this converter. Enter in the US price (in the format 9.87 --no dollar signs or letters) and click "Convert." If you don't know US money, you can use the pound one instead.
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US Version: