Personnally I think you'll pay way to much in shipping if you go the ebay route, been there done that!
You can get used kegs from Homebrewusa.com, they have free shipping on order of $50.00 or more, or you can get them where I got my kegs and everything else you'll need to keg from Ebrew.com (alternative beverage) I've been completely satisfied with their service and low prices. Do you already have the rest of your kegging equipment? They have an entire 3 keg system with all require hardware for $165.00
Cheers!
Sean