My experience is that if you price it right, anything will sell. Either the EE here or Texas Gun Trader seem to be the best places to sell. If you are trying to get anywhere near list price on an "accessory", then it will never sell. As a general rule I have had lots of luck picking up accessories (rails, lights, sights, etc.) at about 50% of the best retail price I can find on the net (which may mean you price at 35%-45% of MSRP). If you are asking more than that, then just plan to sit on it for a while. It is not a matter of he site you are posting on, it is a matter of you pricing it too high for the market. Something like your DD rail is a somewhat niche market anyway so not a lot of folks really looking for a used one specifically. Your are more likely to sell it to someone that thinks "hey, for just 10% more I can get a used DD rail versus a generic new one". Once that 10% premium goes above 20% or so, you completely loose that segment of buyers.