[CaberTosser]

I'm curious how long a typical school bus stays in service, a decade perhaps?

A school bus has 72 seats, if each seat cost an additional $225 over the cost of existing seats then that would be another $16,200 tacked on to the cost of a bus. Divided into a decade that's $1620 more a year or $135 more per month for the cost of each bus. $135 per month divided into each student is $1.88 per month/ per student for the luxury of kids not being sent sailing around the cab of the bus in the event of a collision, or straight out the window in the event of a rollover. Of course if the bus is only at half capacity then the cost doubles to $3.75 per month per student at which point its preferable for the kids to be sent out the window to their death or disfigurement, that's 187.5 extra cents we're talking about after all!!