Cheap Flights - Budget Flights & Cheap Airfare Deals
Use that as a guide to which airline is doing the best ticket price. Once you know which is the cheapest airline for your dates go to their own website and book it on there and it'll be cheaper. Book your hotel seperately, don't do it as a package. Don't book any kind of transfers either, just get a taxi from the airport or get your hotel to have someone pick you up. It'll be much cheaper between the lot of you that way.
Get a "room only" stay at the hotel too as there'll be too many places to eat that you'll want to try rather than a boring hotel breakfast everyday.