I just recently sold my M19, actually. It sold in little under three hours, space out your information with pictures, break it up so it's easier to gather in all the information and have some sort of context. I think that I got a good price out of it, but I probably could have sold it for +$50. Oh well, live and learn.
I didn't want to resort to Ebay, and if it didn't sell on the site I sold it on, I probably would have thought of a different route (I got offered a trade for a high quality knife that I could have sold for lesser value, but with cash it would have been an even offer).