Carpet Dyeing System?

A few shops in my area are starting to offer carpet dyeing services. From what I was told they just, more or less, spray paint the carpets..

1) Why would you use spray paint? Unless there is something i do not know, would the dye just rub/run out?

2) Does anyone know of a system that may be more "Professional"?

3) What should i charge for these services? I was thinking 125 for the mats and 299 for the entire car? Pretty good savings since replacing a carpet can be easily $5,000+.

Any thoughts/advice?

What state are you in megawash?

Northern Washington