On this page, you can buy DocFetcher Pro 1.x for Linux.
Please see the DocFetcher Pro website for a detailed product description.
To make the purchase, click the price field on the right, enter a price equal to or greater than the minimum price, then click the "Buy this" button beneath the price field.
Warning: Be sure to create a permanent account here on Gumroad before buying, otherwise you will not be able to access future bugfix releases.
Before buying, you may want to check out the free demo. This will ensure that the program will actually run on your system.