While 3rd party groups like priceline, expedia, etc. maybe be cheaper, be cautious using them because if you get delayed or cancelled they will not give you any type of reimbursement or credit. The airlines won’t even talk to you if you bougnt a 3rd party ticket. Just something to keep in mind. Try to book directly through the airline. Allegiant, Frontier and Spirirt will be your cheapest options.