March 9 (Reuters) - The New York Stock Exchange on Tuesday set a reference price of $45 for the direct listing of Roblox Corp, valuing the firm at roughly $30 billion. Roblox is among the world’s most popular gaming sites for children and offers a host of games across mobile devices and gaming consoles. The reference price is not an offering price, the NYSE notice said. The opening public price will be determined by buy and sell orders collected by the NYSE from broker-dealers. (Reporting by Ankur Banerjee in Bengaluru; Editing by Shounak Dasgupta)