I'd recommend getting it on Steam. You should be able to get it for $19.99 or less and get the full Ultimate package.
The game still costs $13 a month, and $1 more for each extra character.
Now, keep in mind the graphics are...pretty terrible compared to the majority of MMOs nowadays (including XIV) because it's an old MMO. Otherwise, the gameplay is pretty solid and if you can find some friends to play with you should have a great time. If you play alone...you'll probably get bored and quit really quickly.