Are you buying a new bike from an LBS? I wonder if they would offer a trade in, but you'll probably get very little.
CL can be ok to buy/sell, I've done it but be prepared for lots of obnoxious scam messages. Worse is people who want to pay nothing - I have a crappy car with newish tires for sale on Craig's now listed at $400, and I receive almost nothing but txt messages that say "bottom dollar?" I mean really, your not even going to look? Lots of tire kickers
I'd try eBay or word of mouth. The best time to list on Craig's is a little before or during peak riding season. Good luck!