From what I understand, FFXIV is actually cross platform - you can get the PS3 version, then later buy the PC version and just have to register it to your existing FFXIV account and you'll be able to play your existing characters on the new version.

The only thing that isn't added is the '30 days free' bonus - that only applies to a new account, not an existing one. Buying a new copy of the game doesn't transfer the 30 days free to your existing characters. But other than that, you can definitely get the PC version and use your characters you created with your PS3 version (or vice versa).