A price comparison service allows individuals to see lists of prices for specific products. The Wikipedia article on price comparison explains how price engines work to retrieve data:
One way price comparison sites can collect data is directly from merchants. Retailers who want to list their products on the website then supply their own lists of products and prices, and these are matched against the original database.
Another way comparison sites can collect data is through a data feed file. Affiliate networks such as LinkShare and Commission Junction aggregate data feeds from many merchants and provide them to the price comparison sites.
An alternative approach is to crawl the web for prices. This means the comparison service scans retail web pages to retrieve the prices, instead of relying on the retailers to supply them.
Yet another way to go about it is to aggregate data from user-generated Websites. A new wave of personal finance Websites have popped up in the past year or two: Wesabe, Mint, Expensr… Online personal assistants’ main mission is to keep track of our spending habits, and most importantly make recommendations based on other users’ spending habits. In the background, online personal assistants are gathering valuable information, including products prices. Gathering prices on one side and spending behaviors on the other is one thing. Making recommendations is a different job. As Marc Hedlund, CEO of Wesabe, once pointed out to me:
If you look at our data, one of the places that people go back all the time is McDonalds. Now you look at this data and you say “Wow, this must be a great restaurant! It’s like 5 dollars average price, and people go there everyday” […] We would never want to be in a position of saying: “You are spending a lot of money at the French Laundry, you should really go to McDonald’s”
Point taken! There is a nuance in our shopping habits that price comparison engines have not grasped yet. Each individual will not settle the same way when the decision to save money comes up: Brands, food quality, trends, daily habits… Thanks to the way the US handle macro-economic policies, we now have a Damocles sword hanging over our heads. While Park’n’Save seems a little exaggerated to save money on grocery items, people are ready to compromise to spend less on their regularly-bought items. So who can tell me where to buy what I usually buy… for less?