No need to post to Ebay...just be a little patient. LL (this site) is not really the place to sell this lens. It is unlikely that anyone who reads this list will buy your lens from this site...Most folks here are large/medium format to high-res 35mm - and shoot slower moving objects such as landscapes or their kids...
I have tried to sell a few Canon telephotos here and have had no luck. Instead I have had the most sales from FM (Fred Miranda) forums - I think it is $25/year for membership and you can advertise as many lenses/cameras per year as you wish; also DP Review (Digital Photography review) - membership is free and no cost to sell anything there.
Selling on Ebay with Paypal fees - that will eat up 10% of your advertised price. But your $4000.oo is a good starting point and this is the right time of the year to sell. Just be patient..FM is the best place to sell a supertelephoto from Canon (or Nikon). It might take 2-6 weeks depending upon price...but be patient.
