Thanks for posting here Carol Anne! Definitely put your cards in with your orders. Most people have someplace to keep cards handy--even if it's just all in a stack--but most people file or toss invoices.
You could perhaps offer a newsletter that you could email to notify them of new products.
And, I don't know much about half.com, but perhaps you could "package" some of your offerings. For example, a few books by the same author or the same genre, or a book & a movie or something like that. I know you can package on ebay, but I'm not sure about half.
And, you can maybe find synopses of the books/movies on Amazon or on the book covers or somewhere to put in the full description, so if someone is just "browsing", they will find more info to determine whether the book, movie or CD is something they would like.
Good Luck with your business! Sounds like you & mom will having some pretty great trips!
Enjoy!
Deborah
P.S. If you haven't already, you might want to sign up for the SOHO newsletter, and browse around the SOHO site for other ideas. Here's a link:
http://www.bellaonline.com/site/sohoThe latest article is on ebay trading assistants--you might find it interesting.