Wanted to share one of the methods I use to find some "hard to find" legos. I didn't see anything like this posted.
It's a spin on an article I found: How To Always Get the Best Price at Walmart
I set the preferred store to one of my local walmart locations and do a search for "lego"
Filter your results to only include Lego brand items and items from walmart.
Set the results to be displayed in a list (you don't have to do this, I just find it easier to scroll through)
I start scrolling through the results and add any lego sets that are out of stock online but show "Free Store Pickup as soon as Today" to my cart.
Then I use the Agent Switcher mentioned in the article above (it's a free add-on for chrome) to switch to the mobile view.
This shows me the in-store price for the legos I added to the cart. A lot of the time (not always) they will be discounted since they are out of stock online and local stores are trying to get rid of them. You can then add them to the cart and checkout with in-store pickup.
You can then switch to another local walmart and repeat the process. This has helped me locate some retired legos at discounted prices.