Parts cost (per pixel) for my batch of 32 looked something like this:
Circuit Board (Advanced Circuits) $3
PIC processor $2.67
RS-485 receiver $0.68
Misc. Components $1.00
2 x red LED SunLED XSZE983W $.82
2 x blue LED SunLED XSBGH983W $1.80
2 x green LED SunLED XSBBH983W19 $2.26
cable assembly $1
PCB fabrication (local shop) $3.00
Total $16.23