Jeremy isn't too hard to get ahold of for 405 the Movie...
As a short filmmaker with a moderate level of success for selling to TV, DVD, and other forms of distribution... I do
NOT recommend getting investors or even making a short film that costs that much money. There is very little return on investment with a short film
UNLESS you shoot it for very little money.
The three movies you listed - all had exceptional amounts of uncontrollable luck involved with their financial success. Especially Coven, as they made a feature film documentary around it's finishing. If they didn't make AMERICAN MOVIE, do you think Mark would have ever sold that many copie sof COVEN? The two guys on 405 the Movie used their work computers to render all the graphics, and they were doing FX for feature films already. George Lucas In Love was a USC film school project, utilizing the film school's equipment to shoot & edit (and locations).
All I'm saying is that with a prospectus and business plan, you may want to consider using those tools for a feature film because even a crappy feature will make more money than a great short film. When dealing with investors, getting them their money back & profit is of at least equal import to the art & craft.
Not to be entirely discouraging, short films are more likely to find financing through grants & arts foundations, as they are more for the art and the experience of learning the craft. There is money to be had for more ambitious short films, but investors might not be the best option because there are less options for ROI.
You can get some very good pointers from people like BIG FILM SHORTS, which is my distribution company for short films, and find out what they can tell you for cost versus return.
www.BigFilmShorts.com