All fares are not equal, and it pays (or saves) to shop around. You can often get better deals through discount travel sites.
Be sure to check out the Web sites of budget airlines directly. Some of them don't advertise their prices on fare comparison Web sites. Word gets around anyway, and their competitors will try to beat the budget flyers' prices.
And don't forget about all those add-on fees. Check for baggage and other additional costs before buying your ticket.