I wish I was a member, but to join is $25, which offsets the discount I would get on the Endor Bunker with discount.
I was waiting to join bn after finding they will be carrying the new 2009 sets. Before enrolling, you have to think whether there will be long term benefits for you meaning there will be other coupons provided to members throughout the year to apply to other star wars sets including those coming out in 2010, and if you still have lots to buy.
Or you can split the membership cost with a few friends in your area but then you have to fight over the coupon codes. Also get $25 if you apply for their master card.