I assume The Fall of Delta Green will be publicly available in print at some point? Because I'm planning on backing at the $20 level to get the Agent's Handbook pdf, but next year when I actually have a job I would totally be willing to drop $50 on a hardcover copy of an official GUMSHOE Delta Green book.
I'd imagine Pelgrane Press will be selling it at GenCon next year, and via their webstore down the road. But if it's the latter you'll have S&H to deal with.
This DG kickstarter is one where backing it now for as much as you can ensures you get the stuff, first, without long delays down the road for retail. So I'd recommend trying to scrape up the cash now if you possibly can.