There are cheap (~ Rs.300 =~ US$4) OLED displays available, but beware, there are at least two types of them and they even have same I2C addresses. However, if you use library for one and try it on another type, you get garbage on the screen.

These are the two types I am aware of:

• SH110x (SH1106/7)
• SSD1306

Some are SPI based, some are I2C based. They come with 4-pin vs 7-pin, Colour vs Monochrome vs yellow/blue etc etc. Some say, it cannot be powered from Arduino's 5V output. However, OLEDs are pretty lean on power, so my experience so far is that they work just fine with Arduino's power out and does not need dedicated Vcc.. For libraries with Arduino, I use Adafruit's libraries. They have separate SH1106 and separate SSD1306 libraries.