It depends on where you live, where I live the cheapest airline is called Allegiant Air. You can check out their webpage at www.allegiantair.com. They might serve your area.
Internet is the best source to find out the cheap flights. It will help you to save money and your valuable time. At the comfort of your home you can now search the cheap flights to your destination at the lowest airfare. I would like to recommend one really good website Globester.com to get the cheap flights to your desired place.
Expedia.com is one good source for cheap airfares. You can also get airfare comparisons at Travelocity.com and Kayak .com
The price of flights to Croatia will depend on where one is leaving from. A good place to find pricing is to use a travel site such as Travelocity or Expedia where prices of different airlines can be compared.
From personal experience the best site to find cheap flights to Berlin is Kayak as they have a good way of comparing the prices of different airlines for you. Trip advisor and skyscanner are two other websites that are good to check.
Online auctions
A good place to start when looking for cheap flights is with your local travel agent. Another option when searching for inexpensive airfares is to check out discount travel websites such as Expedia and Tripadvisor.
There are a few good options available for you online. CellularCountry.com is one place online, and FullCycleCellular.com is another online source for used/cheap cell phones. Here is a resource for cheap used cellphones online, including unlocked ones. http://www.cellularcountry.com/
Try Air Tran.It's cheap but good.
The best place to go is Expedia.com or Priceline
There are many websites that offer cheap flights. I would try travelocity or reflag first. I have also had good experiences with expedia. They have excellent customer service.
www.geico.com really is a good site for that.
There are a lot of good cheap online stores to shop from. It all depends on what you are looking for. A good place to start looking is at Oriental Trading or Party Pail.