Web Scraping has become a pretty common practice on the Internet. There are many different web scraping toolkits now and you can generally get product and price information, as long as it is part of the HTML. In general, you would not do a lot of decisioning at the scrape level but would gather all information in a database and sort from there.

The challenge is that web scraping is dependent on how the web page is structured in the HTML. As the store's pages change over time, you will need to address your scraping.