If you want to order online check this site https://www.futurlec.com , the lowest GLCD cost that they have is for a 128 x 64 one ( 24.9 $) , and the shipping costs are very low there, its a very nice site...
If you are looking for really cheap GLCD, then select one of mobile phones' LCD - they are very cheap due to mass production. BW version is about 3-5$, color you can find for 15-20$. Just select the one, which command set description is available on Internet.
I know some Russian companies who sell them, but I don't think that they can send them to you. So, I would suggest you to check on eBay or check with your local mobile phone repair companies. Also, here are two useful links for you about interfacing and pinout of these GLCD:
h**p://serdisplib.sourceforge.net/index.html
h**p://sandiding.tripod.com/Bertys.html
One LCD we had used for a product is $15/pc, but with built-in dual HD61202 matrix dot lcd controller and back light. It can controlled by R/W via bus of uC. another kind of LCD has no controller, but has decoder. User must drive the lcd with external controllers. The price is only about $7 to $8. it looks like a piece of glass.