Unless you are planning on feeding a horse... you may mean straw rather than hay. I only mention it because I was recently corrected on this and farmers have been known to take advantage of people not knowing the difference. Hay is imminently more expensive than straw.
http://www.elsewhere.org/journal/archiv ... aw-vs-hay/Last year we had to wait until pretty close to the event to try to order straw and in fact just ended up dealing directly with the farmer who was driving around the event on a quadbike with a trailer filled with straw bales.
Perhaps this year things will be more organized?