I have a Bum Genius lot, but don't know what to do with them. Normally I just donate our used baby stuff to the local pregnancy crisis place but I don't think they take used diapers, and even if they did, I could use the money. Ebay? Some exchange site? Does it even matter? CL is out because we live out in an area where nothing ever sells...
Try diaperswappers.com. I usually go on our local CL too, you could always post a couple of pictures and see if you get any bites. I think MDC has a trading area too but I'm not sure how active it is.
Something to keep in mind is that with the holidays approaching, this may not be the best time to sell. If you can hold onto them for 2-3 months you will probably have better results (both in how long it takes them to sell and the price you get).
I only charged $2 each, because they were second hand to us and well-used, but still in good shape with lots of life left. But we definitely needed to get some money for them. Every penny counts when you're skint.