How many LEDs make up the sign?
The sign is a grid of 192x64 RGB leds, for a total of 12288 LEDs
What hardware is used for the sign?
How much does the sign cost?
As far as I am aware, nobody sells this sign in its current configuration as-is, complete with computer and software, so putting a cost on it is complicated. I'll offer a price breakdown, but be aware that your mileage can vary widely depending on your sources, size, quality, and tolerance for defects. A new board from a reputable dealer will cost between $50 and $100, once you factor in shipping. For all new, perfectly working components, expect to pay $500 for the boards, RPI, hat, power supply, and wiring, plus a few hours for assembly. However, if you're willing to risk it, you can source used boards from ebay, or place a bulk order from a chinese manufacturer/wholesaler. All in all, I paid less than $200, and the total display has one bad pixel and one column that flickers when another LED is lit.