I'm looking around for a large LCD character display (metre-ish long, 10-15cm high), and on the cheap side (of course)
Actually I think I meant LED display, max $150ish
Hmmm. I'll assume that you mean an LED display.
If you are wanting to display a full character set, you might want to consider using several 5x7 led matrix. See http://www.best-microcontroller-projects.com/led-dot-matrix-display.html for an introduction. MAX7221 driver chips can be used to instead of multiplexing the rows and columns. While the extra chip does add to the parts costs, it will mean bright letters and less pins being used.
Give the dimension of the display that you are after, you'd need to find a LED matrix which contains 10mm LEDs.
I don't see this as a cheap project by the time you assemble the LED matrix displays. Good luck as it sounds like fun.
An LCD TV might be the cheapest option, with an MCU generating VGA.
If it has to be LEDs, you could base it on this XMOS kit, using your own LED array.
Could you work with these: http://www.littlebirdelectronics.com/products/7%252dSegment-Red-6.5%22-Display.html