You can fine the base game for free on the official site or Steam.
Even better for Tolkien fans: the storylines follow in line with the books. Though the game is free-to-play, there are expansions available for purchase which add to the game's story and introduce new items and mechanics. Overall, it's a pretty standard MMORPG in terms of mechanics, but its setting really helps it stand out. You can expect to find the usual World of Warcraft style of questing here, alongside crafting mechanics and the ability to purchase and set up a home. You get to choose between being a Human, Elf, Dwarf or Hobbit before you drop into Middle-earth and explore the locations you know and love with an intimacy that no other Lord of the Rings game has allowed. Sure, Frodo's adventure was thrilling, but we all know we could have one equally as exciting if we had the chance.
Few fictional worlds are as perfect for the MMO treatment as Tolkein's Middle-earth.