...Dan, just beause you see an item at a higher price over at Fred Miranda, does not mean it sells at that price! If you are not in a hurry, you ought to try selling it there at a higher price... if you want to sell "fo shoa", you should do ebay... I sell a lot of stuff on ebay and it is easy... piece of cake for someone who knows how to use a SIRIUS Radio
I'd go Canon Lens as well.... I had the 17mm Sigma lens and sold it quickly... aside from the fact that there was a ton of distortion when having the lense wide open, I was never to happy with the overall, rather flimsy quality of the lens and the somewhat slower focus at times... but then again, I am very happy with my Sigma 170-500 APO lens... even though it is not very tight, but an excellent lens, none the less...
In the end it comes down to your preferences, financial situation and what you need the lens for... to find out what lens is best for you, listen to the pros, try them out and go from there...