I've heard that ordering from out of country places like Redwolf can be kind of risky due to government crack downs on shipments to the U.S. (not sure about other areas).
http://www.airsoftextreme.com is located in the U.S. but again I have only read about the troubles and have never tried ordering from either, but really wanting too.... It seems the biggest problem is money and actually finding a group to participate with...