I've already has some success with my Google group , people are more keen on joining a Google Group then the bogus eBay newsletter/group!
Despite the traffic flowing past the eBay sign-up buttons , custom sign up page in my eBay store and links in my eBay invoices. People are far more welcome to join a opt-in and opt-out Group be it Yahoo or Google.
Google also has a nice button that can be posted on sites where peope just type in thier e-mail to sunbscribe , very handy !
http://groups.google.com/group/slavic-books-russian-bookstore-ukrainian-book-shop
I would also reccomend free online classfieds and not to forget local sites that sometimes drive more traffic and higher prices then eBay and without the fee's !
I say Yahoo auctions USA , and Tazbar are worth trying but the focus should be on your own site ,social networking like groups and free online classfieds