I booked a private tour & my BTB contact was Leslie who setup a website link for each couple in my group to make their payment in advance. The price was based on Euros, thus the credit card transaction made the conversions to US. Last Jan the Euro & USD were almost equal. If you're booking a private tour, request Joshua as your driver/guide who spoke excellent English. Not only was he very knowledgeable, he had a great personality & we enjoyed the tour with him. I can't speak for the other couples, but we tipped him with USD.
We highly recommend BTB & Leslie was easy to deal with via email & helped us create a custom itinerary.