Just in case you've gotten bored with eBay.com (the U.S. site), there's always other options. Take eBay.co.uk for instance. Sure, the shipping charges will cost you and you'll have to deal with all the paperwork that goes along with importing a motorcycle (or three), but if it's the only place you can find what you're looking for, it may be worth the trouble.
An online haven for lovers of old machinery, www.BuyVintage.co.uk is an online company that specializes in "Obscure and Unusual Vintage Vehicles For Sale," and right now they're in the middle of pushing the online auction to a new dimension with a giant internet sale of more than 100 vintage and classic bikes and cars, including the gorgeous 1961 Norton Jubilee 250cc you see here.
For more information, visit www.BuyVintage.co.uk or link directly to the Norton auction online here.