In this new post to his blog Juozas Kaziukenas takes a look at one method for getting the information out of a remote page - parsing it with PHP and XPath (assuming the page is correctly formatted).
When I was writing about how I use web scraping, I was still hadn’t tried using Xpath (shame on me). [...] It turned out, that using Xpath is extremely easy, really. When you master it, you can do everything in seconds. Yes, you need to know how XML works and how to write correct Xpath queries (brief explanation of Xpath syntax is available at W3Schools), but hey - these topics are in 1st year of university.
He includes both some sample code (to fetch a titles and prices for cameras from bhphotovideo.com) and a link to a XPath checker you can use to ensure that your query is correctly formatted. It's good that he also includes a quick reminder about the ethical issue with web scraping - it could be considered stealing depending on where the information comes from and who is providing it.