http://www.polygon.com/2016/12/19/14006908/where-to-buy-a-nintendo-3ds End of December
( 2DS sold out earlier than new 3ds xl )
Nintendo still hasn't restocked it as of now, only shipping a specific amount in stores
*For details read rol's enlightening post : http://gamrconnect.vgchartz.com/post.php?id=8378724
P.S
Nintendo had released pikachu new 3ds xl on the 24th of february causing a huge boost in hardware sales according to npd ( mainly due to january sales being low ) , that thing as expected sold out very fast, currently not a single store has one. As for the other new 3ds xl variants, check in stores or third party sellers ( which of course sellt them at a higher price by 50$ ). This was a first endeavor of replenishing the shelves, a failed one given that the new edition stock depleted quickly.
UPD:http://gamrconnect.vgchartz.com/post.php?id=8425014