I use a First Alert model like
this one. Its battery operated, portable, and has a long battery life.
I agree with you. For the cost of a CO alarm, its not worth the risk while running the generator. I placed mine between the garage (where the generator was running, and the main living quarters. Felt much better having it in place.
Incidently, 3 people were in serious condition following carbon monoxide poisoning in Boynton Beach, FL during the onslaught of Hurricane Frances. Seems thay did not know that you can't run a generator in an enclosed area. I am still amazed that someone would not realize this.
Craig.