TLDR – A chrome extension that checks the website locally on your pc at a time interval and gives you a browser notification so you don’t get an email alert at the same time thousands of others do and miss out on the restock.
A couple friends and I made this extension (instok.org/octoshop) to help with the inventory shortages for the Rift S.
The extension is supposed to show you other retailers have the product that you are looking at (if you’re on the Best Buy page, it will show Newegg, B&H, etc links to the same product without price gouging resellers) and most importantly set in-stock notifications that will notify you when the Oculus is back in stock. It checks the website periodically to see if the add to cart button is back online so it should be faster than email notifications that some websites have (which is important for high-demand stuff like the Rift).
The most important thing is it lets you set price drop notifs for places like Amazon that say it is “in stock” but in reality is just being resold at $700. Hope this helps people get the Rift during quarantine and just shopping in general!