Always check Ebay for Yakima bike attachments. There's always a bunch on there, new or used. If you're patient enough, you can usually find some for much less than retail. Don't be afraid to buy used... Yakima products are very durable. I got a used Steelhead with a couple scratches for much less than retail. Why buy new when it's going to get scratched up with use anyway? Also, don't bid early. Put the one you're interested in on your watch list and bid at the last possible moment to get the best price. People who don't understand the game always bit too early and end up driving up prices. Have a minimum price in mind and don't bid on anything over that. It might take you a couple weeks before you finally get what you want... but you'll save $.

Buyer beware though (a given with Ebay).