Web pages change all the time, so why not use some python to monitor web pages you're interested in for free?
It's a python program that monitors a web page and e-mails you when a change on that page is detected.
It uses selenium to open a web page, screen shot it, and then screenshot it again later to check for changes. This happens repeatedly. Changes are detected using perceptual hash differences between two screenshots (the old screenshot and the new screenshot).
I initially thought that scraping the DOM might be a good way to look for changes, but it's just too much work writing a new DOM scraper every time you want to monitor a new site. Comparing screenshots at different points in time seems like a good way to get around that.
First, make a virtualenv and install the dependencies by running the following 3 commands:
virtualenv venv
source venv/bin/activate
python3 -m pip install -r requirements.txt
Then fill out the e-mail (do NOT use your main e-mail, use a dummy account for safety!), password, and url you want to monitor in the main function. Also, I've included the binaries for chromedriver but feel free to download the new ones at the official chromedriver website.
Finally, run python3 monitor.py to start monitoring a website.