To Trail or Not to Trail

Some days back, Katherine Center, a writer friend, sent me the link to a book trailer she had created for her new novel, Everyone is Beautiful: http://katherinecenter.wordpress.com/..., and of course, when I saw it, I wanted one, too--for both Palace of Illusions and for my new children's fantasy novel,  to be born in a week: Shadowland.

I wanted to find out what's involved, time, effort and money wise, and so I (what else!) googled the term and came up