For small batches, I have found the 4 liter Carlo Rossi bottles are great. A number 6 bung for the airlock. You can get them from friends or bottle recycling places. Follow directions for 1 gallon batches, increasing slightly to account for about an extra quart.
Since they quit making carboys in Mexico we have had to buy Italian carboys. Mexican carboys were a lot cheaper due to lower wages but more due to NAFTA. With the Italian carboys they pay much higher wages plus shipping and taxes. It all trickles down to us. Used to really tork me off when people griped about NAFTA saying it was taking American jobs away but in the next breath they would gripe about the price of something. About 3 years ago you could buy a 6 gallon Mexican carboy for $17.00. Better Bottles used to cost twice what a Mexican carboy cost. In regard to the OP question, like said, check Craigslist if you have a local site. Thats your best bet to find on the cheap.
Boy I wish I could help some of you folks. I can buy 5gal glass for $10.00. The local water botteling plant has hundreds of them sitting on pallets in thier warehouse and they would like to be rid of them.