WuBook gives you a tool to enter reservations manually directly from the control panel. This tool is called YouBook. With YouBook you can use the standard rates or insert discounts in real time. It is possible to give a status to each reservation: confirmed or waiting for confirmation.
If a potential client asks for a quote, you can create a reservation waiting for confirmation on YouBook and send the client a link where he (by himself) will be able to confirm the reservation/quote by giving his credit card details. This way the status of the quote will change to confirmed and guaranteed by credit card.
If the client refusses the quote, need only go on the details of the reservation to cancel it. In this case, the availability that had decrease with the creation of the unconfirmed reservation, will increase again automatically and, in case you have the Reservations Fees version of the booking engine, this will not account for in the commissions report.