Well, $1 is only for the first three games. Those bundles aren't meant to be that profitable for the site but to give most of the money to charity. They just contact developers of the games to ask them if they want to be in. Both developers and site take a bit of the amount raised. If you want to check out more sites like this, there is Humble Bundle which is the biggest one out there and Bundle Stars that is very similar to Indie Gala. Thanks for checking the post !