To access Favorites, tap the search bar at the top of the price list page, then tap My Favorites.
To add/remove a station to/from Favorites, tap the station name in the price list, then tap to select the heart icon in the top, right-hand corner of the station details page.
To add a station to Favorites while reporting a current price, be sure to check the box beside "Add to my Favorite Stations". From there, select the Favorites list to which you wish to add the station, and hit, "OK". Then hit, "Submit".
To add a station to, or remove from Favorites without reporting a current price, go to Manage Favorite Stations. This can be accessed by clicking the link at the top of the Favorite Stations List, itself, "[Edit my favorite stations]".