Drupal 7 Search Redirect (similar to the old AOL keyword search)
If there is only a few you and you don't need any advanced matching you can add a path alias for the search path pointing to the preferred page.

E.g. searching for brand a gives you the path search/node/brand a. This path you can add as a path alias at admin/config/search/path/add pointing to a node of your choice.

For more advanced matching (and a more solid solution) you should probably hook into hook_search_preprocess() and do something along the lines of your example code.