Looking for some market research stats please

[Cereal Licker]

I am writing a business plan for a new steampunk clothes business that I am starting, but I don't know where to get statistic for the market research portion of the plan.
Could someone help me by perhaps suggesting where I could dig up stats on revenue from sells of steampunk clothes \ products in conventions or online? or statistics about number the number of people attending in steampunk conventions in the USA and UK, or other countries? It could help me a lot.