gunbroker.com is by far the easiest way. But, most expensive way to get it. Other than that, no online retailers have it. If they do, it's a scam.
A want ad in the classifieds might get you someone local, to you, that would be willing to help out (99% of us can't ship powder).
Offer up something for trade. If you have Berger, 30 Cal, 215 gr Hybrids to trade you can probably have H1000 by sundown today.
I'd seriously consider buying some of this, if I needed something very close to H1000 (in-stock right now):
www.natchezss.com