There is a highly-rated merchant on eBay selling the Canon EF 100-400mm f/4.5-5.6L IS II lens for $1,649 including free shipping. The normal price is $2.099 after $100 rebate. As The Wildlife Ho-tographer, this is my favorite 'L' medium zoom lens in Canon's EF lens line up. You can read my review of this glass here.
I have taken this lens all around the globe on many wildlife photo shoots, from the high Arctic to the Southern Ocean. You can see my lens recommendation for nature and wildlife photography.
You will not find a link to this merchant because I do not accept any advertisement, commissioned link and tracking cookies on my Blog or website. I am completely unbiased in my recommendation and have no conflict of interest. You can find the listing easily by Googling it yourself. See my equipment bag, works and images taken with this lens on MichaelDanielHo.com