Now don't quote me on this, I read about this a few weeks back but the information still looks pretty current from my searches of news and posts on Google.
The Switch being sold out is pretty widespread due to the Coronavirus, since there is a limited component supply coming out of China.
The best information I've found is we may not see more till the end of April. I don't know about Best Buy specifically as it's general information, but like I said it's widespread. So I can imagine all stores will be affected the same pertaining to availability.
It may not be what you wanted to hear, but I hope it helps. If you would like the news articles and links I found, feel free to PM me.