which is the best online store?

I am based in London UK, not a professional photographer but not bad though.... I have been using Internet for shopping most of the time,,, and now when i feel the need to update my camera from Yashica to a better brand though the one i have been using is not that bad, still,,,,,, I tried pricerunner.co.uk kelko.co.uk and some other price comparison sites, on checking some good stores in UK online through kelko e.g. www.microglobe.co.uk , i compared the price of an article manualy with one in a US store, the price in US store was quoted without VAT,shipping cost, and lense cost, I need to know if the prices in US are better then UK,,, or it effect the same with the inclusion of all excluded factors above.??Thank You