In The Labyrinth is a complete RPG of The Fantasy Trip by itself now; in fact it's now titled The Fantasy Trip: In the Labyrinth. There is no Advanced Melee or Advanced Wizard anymore, but there are standalone fighting games of Melee and Wizard, which you don't need if you have The Fantasy Trip: In the Labyrinth.
Correct: your full acquisition list is:
Legacy Edition In The Labyrinth core book
A hex mat (e.g., from Chessex)
Appropriately sized miniatures or markers for your hex mat
The minimum investment for getting a combat map and markers would be to get the new melee/wizard pocket box game. But if you are going to play as a fully fleshed out roleplaying game and you already own some miniatures, you'd rather put that money toward the Chessex battlemat.
That said, once you get all the ancillary stuff together, you might be close to the cost of the Legacy Edition boxed set.