There are no hidden costs, but there may be additional ones. If you book a Blue Badge Guide for a tour that involves staying away from home, you will be responsible for the cost of the guide’s accommodation, evening meals and soft drinks. You may also be required to pay the guide’s travel expenses to and from your meeting point, and you will need to pay for their entry ticket to any places that do not offer free entry to Blue Badge Guides.
However, your guide will agree all charges with you beforehand, so there will be no nasty surprises at the end of your tour.