I guess the different formats may appeal to different groups of people. The gallery audience expects larger works and in that environment it's possible. But would you consider the type of people who go to art galleries, "mainstream?" It's natural to want to appeal to people like ourselves, because they would be the most likely ones to share our appreciation of fractals. But I think the jump to a 'mainstream' audience probably means using a more common medium, and one which might not be as well suited for displaying fine art and is probably lower resolution and higher volume. One possibility I can think of would be corporate Christmas cards (high volume mailing to customers) for high tech or technology companies (computers, electronics, research, medical, pharmaceutical...). They might like something "different" and find the technological, scientific aspect to fractals compliments their corporate image.