We have taken a look at price comparison add-ons for Firefox (see Firefox Price Comparison or Price Comparison With Invisible Hand For Firefox for starters) and Google Chrome (View Item Price History Of Amazon, Best Buy And NewEgg or Top Google Chrome Shopping Extensions) in the past.

BookInfoLine is a userscript that is currently only compatible with the Firefox web browser. The userscript concentrates on book price comparison. It supports several of the largest book retailers in the world and concentrates largely on the English book market. It checks for instance on various Amazon stores, eBay, Walmart, Google Books, Barnes and Nobles and Abebooks. The userscript furthermore checks for audio and Kindle editions as well.

How does it work then? You simply visit a store page that lists a book. The userscript displays an overlay window at the top right, which, when pressed, displays pricing information from all supported online stores.

Links point directly to the book page on the shops that carry the item. All it takes is one click on the shop of choice to load the page and read up on the details. The userscript does not include shipping and handling costs in the price that is fetched from the online book stores. This means it is still up to the user to make that calculation to come up with the best price.

It is possible to save lots of money on book purchases if the userscript is used for price comparison. Then again, it is mostly of use for users from the US and UK, and not so much for users from countries where English is not the primary language.

Firefox users can install the BookInfoLine userscript directly from the userscript.org website.

The Firefox add-on adds itself to the right-click menu. If a phrase has been selected on a webpage it will offer to search for it on various price comparison sites but also directly on shopping sites like eBay, Amazon and various other shopping portals. The sites that are displayed in the right-click menu can be configured by the user. There is however no option (currently) to add custom sites to the list. Only the sites that the software developer has added can be selected.

There is however a large selection of price comparison sites and shopping sites available and it is up to the user to add the ones that he is interested in or regularly using.

The selected shopping portal or price comparison site will be opened in a new tab in Firefox. There is also the option to search for the product in all sites in a category. This simply opens all of the sites in a new tab.

The author provides an option to suggest new websites which might be added to the database of sites at a later point in time. The Firefox add-on comes with a second option. If no text has been selected a right-click and the selection of RightClickBuy from the context menu will open a search form that can be used to search for products on a selected website.