Finding it in store like target and Walmart is pretty much never going to happen, the people that stock target and Walmart are 3rd party vendors. The vendors get paid off by people to give them a heads up before they go stock and it’ll probably never hit the shelves. Perfect example I went to Walmart last Friday at noon, there was a line of 8 people waiting since 8am for cards. The cards they wanted ( which everyone wants) never hit the shelves.
I’m currently working on building my website, I’m set up with a couple different distributors to receive product but I only get hobby boxes not retail stuff. To answer your second question yes hobby boxes are definitely going to produce bigger hits and higher valued stuff. There’s occasions where retail product has retail exclusice stuff, but most of the time biggest hits are going to be in hobby boxes.
I sell boxes typically when the product first comes out but I do it at market value. Next big basketball release is coming at the end of the month.