I sell knives here and on e-bay. There are two major differences to my mind.
First, there are no listing fees or final value fees or fees of any kind to sell here, besides the $25 per year that it costs to become a gold member. Therefore, if I sell a knife for $90 here it's about the same as selling it for $100 on e-bay, in terms of my net return.
Second, the buyers here are sophisticated in the extreme, so you won't have much success on the exchange unless you are selling quality knives at a fair price. If you are looking to sell Spydercos, and you are selling them at fair market value you should have no problem at all.
C'mon, dive in -- the water's fine!
And regardless, welcome to BladeForums.