1/ In a bird's nest

cheep cheep
2/ Amazon and Ebay are obvious examples of on-line sources.
NOTE however: a/ Most will be 12V, b/ Displays are likely to be 240 line in smaller sizes, or 480 ... higher prices likely for higher resolutions
3/ Without mentioning your country/location, any price/model guidance offered here is probably irrelevant as price comparisons offered usually take no account of shipping, local taxes and import duties (not forgetting the carrier's surcharge for collecting duty if payable)
4/ A small composite display is likely to be difficult read for any length of time - avoid use of colour in text to help make it clearer (no subcarrier)