Yep....I've seen it, but I am not moved enough to give up a large bill for it by the time it gets here. That even-trade 686-4 for the 681 ND "M" is starting to look a little better. If my 686 was a ND....it would be a no-brainer. I just prefer the changes that were made to the gun thru -3 in the 681 (last run) and -4 in the 686.
Imported 681's appear to be plentiful down near the $525 range, but you also buy that deep roll-mark on the barrel. I have a finisher that can take that off, but by the time I do that....I'm back in the $700 range and they are ND's as well.
I guess us gun-nuts put ourselves in these conundrums....ain't it fun.