Are you required to buy items when you choose the Legendary Object options at the village?
According to the rules for Tokaido: Crossroads on the Fun Forge site (emphasis mine)

Now, when a Traveler stops at a Shop space, he must choose between:

Buying Souvenirs (basic game rules).

Acquiring a Legendary Object.



While the base game rules (Souvenirs Only) say

The player draws the first 3 Souvenir cards from the pile and places them face up in front of him. He can then purchase one or more of these cards by paying the price indicated on each card.
Note: A traveler must have at least 1 coin to stop in a Village, but
he is not required to purchase any souvenirs

In the base game it is clearly possible for the player to end up with only Souvenirs they cannot afford, in which case they can purchase nothing, as well as simply choosing to purchase nothing.
It seems fairly clear that the player must first decide which of the two purchase options they will pursue, and having made that decision the other option is no longer available. Having made that choice the same rules would seem to apply in both cases: if there is nothing they can purchase, they are out of luck; even if they can purchase something, they don't have to.
Further, unless you're playing with the 2-3 player variant for Crossroads, all players have perfect knowledge of what Legendary Objects are available to purchase. There are 6, 2 each costing 1, 2, or 3 coins, and any purchased objects are visible in front of the player(s) that purchased them. In the variant where 2 cards are discarded, they will have perfect knowledge after looking at the Legendary Objects once, and the goal of that variation seems to be to slightly increase the risk/reward given the large number of stop opportunities with so few players.