As the big day inches closer, what to do? Where to go? Have no fear, Eagles fans. We're here to help. Although the local costume shops we checked don't have them, they are readily available on eBay. A website called KickPushSkate.com also has a limited quantity of "underdog masks" for $29.97, as does Spirit Halloween. Another site, Oldies.com, will donate a portion of the purchase price to the Philadelphia School District, Johnson's pet charity. All the sites guarantee delivery before game day. Arrivals any later than Feb. 4 would be a dog-gone shame.