We do not control the conversion of the GBP cost into USD, EUR or any other currency.
The conversion is done by your credit/debit card company, and the rates change daily.
Some credit card companies offer very good rates of exchange, others not so good ones.
We have no way of knowing what rate your card issuer will use.
You can use the live currency converter on each product page to get an approximate indication of current rates.
Remember the total costs will depend on how many products you are ordering, and there may be shipping or tax charges.
There are services like TRANSFERWISE who will tell you the currency equivalent cost up-front using mid-market exchange rates and low wire-transfer fees. Email us if you want to use this type of service.
We hope to offer USD and EUR pricing in the future.