Thank you for your inquiry.
We do not have knowledge of the guest/service fee that HomeAway/VRBO applies. HomeAway/VRBO charges that directly to the guest upon confirmation of a booking. This set up means that a HomeAway-sourced booking in your account will have two separate charges from different places for the guest - the service fee charged by HomeAway, and the reservation's payments (rent, fees, deposit, etc.) charged by MyVR.
If the listing is managed within MyVR, sending a quote in response to a HomeAway/VRBO inquiry is not advisable because the guest will always be funneled back to the HomeAway/VRBO listing to make the booking (HomeAway strips out any pre-booking links from messages - so the MyVR Book Now link will not be delivered). On the HomeAway/VRBO listing, a quote is generated automatically using the setting in the MyVR account. So if you manually send a quote, it could be different than what the guest actually gets charged at booking.
One workaround in the event you negotiate a non-standard rate with an HomeAway-sourced guest prior to booking, is to set up a special event rate in MyVR for just the dates proposed - that way you can match up just that time period to whatever was negotiated.