I would buy it wherever you can get the best price, as long as it is an authorized DJI reseller. If you buy at a local place like Best Buy, you have the added convenience of an easy return in case there are any issues with it and you need to take it back.
The Fly More package is OK but depends on what price you get for it as opposed to buying the components separately. You will certainly want extra batteries and the charging hub is nice to have. The carrying bag they give you in the Fly More package is totally worthless. You will most likely want to purchase a nice custom fit case for it.
There is no
Smart Controller for the Mavic Air. Only the standard controller that comes with it.
Personally I would get the
MA, a couple of extra batteries and a custom fit case. Then add more as you see how you use it.