Sort of. Amazon doesn't exchange one-for-one. However, if you search the lens you have on Amazon you can see at the bottom of a listing that they will give you a gift card in exchange for your old lens. I searched "Nikon 18-200" and followed the trade in link at the end of the product listing (http://www.amazon.com/gp/search/ref=sr_1_ti_5?rh=i%3Aelectronics-tradein%2Ck%3AB002JCSV8A&keywords=B002JCSV8A&ie=UTF8&qid=1387741034&sr=1-5-ti ). Amazon will give you up to $360 on a gift card for your lens. You can then apply that gift card to the purchase of a new lens.
Used 18-200's are selling on Amazon for $479. You can also set yourself up as a seller on Amazon and sell your lens through the Amazon website. You might get a few more dollars for the lens. If you have other things to sell it may be worth the effort. You can scroll all the way to the bottom of an Amazon page and find info or go to this link: http://services.amazon.com/content/sell-on-amazon.htm/ref=footer_soaT?ld=AZFSSOAT