I have quite a popular site and I am in the early stages of adding a shop to it to sell related goods, I am in the uk and the site is a .co.uk however most of the visitors are US. If I were to sell goods, do you think it would be better to have them priced in dollars rather than £ GBP, I know people in the UK are a lot more familiar with the rough currency conversion into dollars however I get the feeling that folks in the US just have no idea how much £1 is in $ and if I priced in £ even offering a currency converter I may be turning people away. I just want the best conversion rate so maybe everything should be in dollars with an option to convert to £ and Euro's? The thing that holds me back is that I would be buying wholesale in the UK and with the fluctuating exchange rates my margins would therefore fluctuate.
i would display the GBP as the base price and the USD price at the prevailing rate, i have seen this done on quite a lot of sites. you should be able to plug in a currency conversion. If you are any good at programming, i think XE provide the raw data to use http://www.xe.com/sitemap.htm#webmasters
I would leave it in Euro's. Due to the exchange rate plus shipping charges, do you think you would have a lot of US customers? Granted, it would depend on what you were selling, but the UK is a bit far away for most people to order products, I would think.