We also take requests for any store listing URL and even if we don't support it right now such as Nike for example we will prioritize it and get it added to our queue to support tracking it.
The interesting thing about your point that Amazon and other merchants that have a "notify me" button is that they don't really work for users. However most of their methods are to process new inventory, their notification process is disconnected somehow and delayed for some reason. From the community I've been working to build as well, they all say the platform is much faster than the stores' versions.
The Staples price you show is $4 more than the price I paid.
I've actually been toying with this concept for a weekend project, essentially a quick 'n dirty node daemon process that checks prices periodically, for sites it knows how to. More often than not the data is just sitting there in JSON in the <head>, so you wouldn't necessarily have to scrape it either. (e.g. fossil)
Open source the project to let others send PRs for other sites...
Toss in a sendgrid key for emails and you're all set...
Prices are competitive information, at least competitive enough to warrant obfuscation and preventing scraping.
And, the more sources you have, the more likely things will constantly fail. Scraping is always fragile.
One of the first web-scraping projects I ever built was to find the lowest price for Clif bars. I ate about 365 per year, and in only 45 minutes of programming a cron job and push notifications, I easily saved $100 that year.
Services like Crawlera act as a proxy that also forces you to be nice. If anyone is getting into this, I would recommend they use a service like that to scrape at scale.
Let me just supply the URL and the price string... and let it automatically figure out the right <div> or class or id or surrounding text it can be extracted from. And if it ever breaks (can't be found, or returns something in a different numeric format) then just notify me to visit it and see what's up.
Command-line is one way to do it (can be the canonical version), but then a browser extension makes it even easier. You'll need a headless browser even from the command-line in any case, since the product info isn't always in the HTML at all.
I think that’s a difference between a seller “owning” the listing for an FBA SKU such that Amazon can see in their intake logistics that more of that item is coming to their warehouse; vs. a non-FBA SKU where they don’t have that visibility; or vs. an item that has gone defunct where no seller is claiming responsibility for restocking the SKU any more.
Whether toilet paper, a webcam, or whatever random thing that's been out of stock for a month -- set a CCC alert at some fairly high price and it'll e-mail you when it's back (below that price) -- even if the price you set is higher than it's ever been before.
I'm actually really surprised they haven't bothered to make that functionality explicit -- since it's not obvious that it will work -- and it's so valuable especially now.
(Confusingly, sometimes Amazon pages for out-of-stock items include a button to notify when something is back in stock, but most don't. They just say "we don't know if or when this will be in stock.")
I've become so reliant on CCC it really bugs me I can't use it (or an equivalent) on other sites -- e.g. Target, Wal-Mart, Best Buy, Nike, J. Crew, whatever.