Reaper, here's the thing, just coming in and asking questions about values of boxes sometimes is frowned upon here, as it seems you're not really interested in being a part of the forum but just selling your stuff and getting out of here. We're a forum for boombox enthusiasts, we're not here to value your stuff so you can make a fast profit. I mean we can and someone might help you, but I'm trying to tell you these kind of posts are usually not answered. Why should we help you price your RX-6400 when you're probably just going to turn around sell it and never come back ? We're not a resource for ebay dealers and if you want some help we expect some contribution too. If you're actually interested in boxes, make a post in the introduction section etc. If you just wanna sell you stuff good luck, I don't know much about the RX-6400, but if it's fully working it could be worth some money.
Peace