the 20$ processing fee is a constant with all skyauction transactions
in addition they usually have a charge per night that is added to your final per night bid...
total thus would be
bid + tax/room surcharge x no of nights + processing fee
nightly stays are not as cost effective as the full stays.....
sometimes it is just as useful to grab a 7 night auction, even if you are only going to use it for 3 4 or 5 nights and in most cases with this type of auction you will be getting MORE than just a hotel room.....