I don't really see what the NES classic has going for it, personally - the interface is basically the only thing it has over any pi-based solution, and even that's debatable, depending on how much of a retroarch loyalist you are.

They're trying to sell them, they just did it badly and are now scrambling to catch up. That said, they are slowly catching up. Restock frequency has been slowly increasing.

If you want one, set up alerts on brickseek.com, nowinstock.net and zoolert.com. Every few days they pop up somewhere online or locally. They're still scarce but it's possible to get them. Amazon had stock for almost an hour when I bought one a few weeks ago. Using these alerts I got two in the last month. One for me, and a second just for the controller. The official controller is even harder to find than the console.