Will reducing the cost of Holy Water or improving its effectiveness break things

My L3 LMoP group are planning on picking up some holy water to help with zombies as they’ve heard to tales of undead (old owl well, and thunder tree), but I think they’re going to be very disappointed to find its 25Gp, but is single use, costs an action, affects a single target, and only does the same damage as a greatsword swing.

Essentially, it seems to be only as good as a single decent fighter attack, but uses an action and costs 25Gp. Given that an average L3 PC might expect to do say ~D6 +3 damage with a typical attack, this means they’re getting about 3 extra damage, once, for 25Gp, which seems absurd. Plus it only works on certain foes.

Am I missing something?!

I’d like to make this work for them, so I’m considering some changes to the rules for Holy Water:

  1. Reduce the cost – maybe as low as 5Gp, given that they have a paladin who is visiting a temple to make his oath (this allows me to keep the price higher on other occasions if they did find a way to abuse it)
  2. Make it more effective – maybe an AoE effect?

Will this break the game, or be something they can heavily abuse later?