Reading plates is likely a small fraction of overall costs. Consider, with 220 people cars in a trial your going to need someone to write a manual / answer help desk questions / etc. which have nothing to do with the actual device but do add costs.
As to the device it needs to do more than just read licence plates. It must compare them with something which means it needs to get over the air updates for a list of licence plates. So, now you need some back end system to get important lists of licence plates from various other systems. As to the device, how much coverage does it get aka does it need multiple cameras.
And on it goes.
