Nowsaday, I don't think there is any ICO worth to invest anymore. I had so many bad ones lately. Better off purchase them after they released at the exchanges.
What you are thinking is the correct thing because what ever the ICO worth is when they get listed and as soon as the bounty coins are distributed you can surely expect the price to be dumped and you can get below ICO price for sure as i have seen in almost all coins even if the project is good