Okay, so here's my secret (I did some Googling as well). Chrome has a "Page Monitor" extension that will tell you when a page changes. It stays up in the little extensions at the top right (after telling it to monitor the page), and then turns green when something happens. So I kept the 2 BB tabs up and had the Page Monitor watch them. The problem is, I kept repeatedly missing when it popped up while I was working, gaming etc.
You can add a "chime" sound but I rarely have my sound on, it's always muted. Last night while playing Fortnite on my PC (I'm a nerd), I set my MacBook Pro up next to me with the sound on LOUD, and gamed for awhile. When I heard the chime, I refreshed the page and was able to add it to cart. Downside is, my Visa always wants an extra text verification from BestBuy, so here I am with it in the cart trying to check out and freaking that the Visa is doing the text authentication.
It was amusing, but I got lucky. I'm really hoping the unit doesn't disappoint and it works well!