There wasn't a fixed set price, either measured in Ether or Bitcoin. The ICO started with 1 Ether getting you 100 DAO units, rising up daily upto 1.5 Ether getting you 100 DAO's until the ICO ended. During the ICO, the price of Ether was on the rise as well.

So measured in Ether, one could say the ICO price was like 1.25 Ether for every 100 DAO's. But this isn't accurate, since >75% of all the DAO's were purchased at a rate of 1 Ether for 100 DAO's...
Measured in Bitcoin, taking day 1 in account, the price calculated from DAO > Ether > Bitcoin, was slightly less than 19k for a single DAO.