from china
You can buy cheap phones online through sites like amazon.com or even ebay.com . There are many physical sites that offer cheap cell phones like Chinatown.
On the internet.
In the market on Jupiter
At the flea market.
Walmart is cheap. Dollar stores have cheap phones too.
I think online is where you could find an good place to buy cell phones cheap. I have found other things there that are cheap. It could give you the same results.
You can buy cheap unlocked phones at retail electronic locations such as Best Buy and Future Shop. You can also buy these phones at big box retailers such as Walmart as well as at online shopping sites such as eBay,
walmart
you can buy a cheap phone in walmart, I got my brand new Samsung galaxy II there for $1.04, you would be amazed of the good deals you can get on phones there....
Consumers may find cheap unlocked cell phones for sale on the Internet. A variety of auction-style websites and popular electronic merchants may feature cheap unlocked cell phones. If you buy an unlocked cell phone, you may be able to use the device on another service provider's network. You might be able to buy cheap unlocked cell phones through certain classified newspapers.
Look on eBay or craigslist, people upgrade phones all the time and sell their old ones. Just keep your sim card and put it in the new phone. or you could just go on websites and look at the cheapest and save up :)