Things in both the retailer and private sales sections change on a daily basis. We could tell you there are 10 such guns now, you get verified in 2 weeks, they're all gone, and you won't see one for weeks after that... If you're in the process of getting verified, just wait till you get your access and you'll see for yourself.
Also, as Amos said, even if you don't find the exact gun you're looking for, you can always start out with another base model M4 and get aftermarket parts for it. There's always a bunch of RIS / RAS kits and stuff for sale in the private sales area.