When compared points-wise with other units this seems about right (Compared, say, to the Chaos Chariot, they hit a bit harder but with the Orc Command values they aren't as likely to hit as often).
Having said this if these were available in the Orc army list at 125 points per unit I'd take them like a shot, and as many as possible. They're highly likely to punch through whatever they charge (especially in conjunction with a hero or some magic) and the low cost of other units should mean I can take 6 in a 2000 point list without having a stupidly low break point. With 4 attacks they're also less vulnerable to counter charges which somewhat negates the weakness of other chariots.
I'd try them at 125 (it's not like the Orcs are the toughest army) and see how they go. Perhaps limiting them to 1 per 1000 points might be an idea?