You can buy your AMA membership at any event that is covered under AMA rules and regulations. Or you can buy it online. If you go to Atco, you can just buy your membership right there. If you go to Wildwood, you can buy your membership right there. It is in the AMA's rules that a promoter cannot put on an event being covered under the AMA's insurance blanket without offering an immediate membership to riders. It is also written that the promoter cannot charge more than the AMA is asking.
New Egypt is not covered under AMA insurance so if they race there you do not need to be an AMA member. They have their own insurance carrier. It is a good thing to become an AMA member anyway. Believe it or not, they are here to help us.
The New Egypt 2010 schedule is listed and it doesnt have any quad events listed, that is the only reason I am still a bit doubtful about seeing a race there. We can keep our fingers crossed though.