If you get the Atlus Newsletter email they have a survey for everyone to fill out about pricing, extras, and systems.
Take the survey The results so far. Seems that most of the people who have taken the survey have bought a lot of Atlus games. The most popular recent titles are Persona 3 followed by SMT and then DDS 1&2. Extra stuff people like are art books, soundtracks, and figures. Most of the people would play 10 dollars plus to get groovy extras with the games. And the most appealing platforms are the PS2 followed by the DS.