Infared Thermometer ?

I would like to purchase a infared thermometer but have a question.
It seems that some read up to 500 deg F and cost about $30 and some read up to 1000 deg F and cost $60 and up.
My question is for automotive use, which one is better?
If you are measuring exhaust gas temps on the header, what would be the max temp reached?
If less than 500 deg than the $30 unit would be fine.
Does anyone have any input on this?

Thanks