According to Drug Patent Watch [1], the patent for Advil expired in 1994, allowing other pharmaceutical companies to produce generic versions of the drug. This means that there are many generic versions of Advil available in the market. The price difference between Advil and its generic versions can vary depending on the store and the location. CBS News [2] reports that generic drugs are generally cheaper than their brand-name counterparts. The cost difference can be as much as 85%, making generic drugs a more affordable option for many people. GoodRx [3] notes that the price difference between brand-name drugs and their generic versions can be significant, especially for people who don't have insurance. Generic drugs are often less expensive because the manufacturers don't have to spend as much money on research and development or marketing. Additionally, the competition between different generic drug manufacturers can drive down the price even further. Therefore, it is likely that generic versions of Advil are significantly cheaper than the brand-name version. However, the exact price difference can vary depending on the specific generic version and the location where it is purchased.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ADVIL
[2] https://www.cbsnews.com/news/generic-and-store-brands-vs-brand-names/
[3] https://www.goodrx.com/healthcare-access/medication-education/brand-vs-generic-drugs-whats-the-difference