I'm a travel agent Serenity and I can tell you Kayak.com is an awesome tool to FIND the availability of a set and the pricing.
Go to kayak, punch in your dates and airports (always use major airports as flights to and from hubs are cheaper) and when you find your lowest price (best prices always leaving and returning on tuesday / wednesday) ...
write down the airline name, flight number and depart/arrival dates. Call the airline directly and that way you'll get the best price possible.