Yep, sounds like Zofran.
I just picked up a 4 day prescription for it on Tuesday and it was $414 for 12 pills. Luckily, my copay was only $27. I was on Phenergan (sp??) for a week to help with all day morning sickness/naseau and it didn't help, so they tried Zofran. So far, so good. I actually feel like myself for the first time in 4 weeks!
I know the pharmacy I go to always substitutes generic drugs unless specifically asked not to (then my copay is $10). They didn't substitute the Zofran, which makes me think there isn't a generic for it. Since it seems to be working I hope my doctor can prescribe a longer prescription for me since I don't want to have to pay $27 every 4 days (but it really has been so much better!!!!)
I hope your son feels better soon. I felt relief almost immediately after starting on the Zofran.