While I can totally understand your plight as somenoe just trying to start up something on your own and make it out there, I think you're going to have a rough road ahead.
in this day and age, it's not the quality of the product that will carry you, but how you market and distribute it. (WotC has proven this time and again through their subpar products)
In your case, the pirating, especially if the product is good, is almost inevitable.
Having said that though, there are ways you can that shit work for you. Like one of the guys above said, if playing the game requires the book at hand, then the PDF is just a teaser at best, since loading it up on your laptop and printing it off is just not the same.
take Spirits of the Century, for example, they've gone ahead just put their SRD out in the open to increase their product exposure.
from several of the comments I see in this thread, that is precisely your problem right now. you have no exposure. while getting your shit pirated sucks and all, it DOES increase your product circulation. With a bit of concrete data and research, you might be able to convince a publishing firm to put more money behind product once they realize how popular it is.