That depends. Most products are billed in US$, while others are billed in € or £. The currency and amount will always be shown whenever possible when adding a product to your shopping cart. Some software settings may not let us specify US in front of $, or may not let us specify a specific currencies. If a price is shown without a currency designated, you can assume it will be in US$.
Please be aware that your bank may charge you in your local currency, not the currency we bill in. Your bank may also charge you a conversion fee, processing fee or other fee in order to be able to process your payment. Such fees are between you and your bank and are not reimbursable. To avoid any surprises, please check with your bank before purchase so that you will know exactly what you will be charged.