Number of explosives in the game right now is set, but you will be able to get more or even craft them in the future. If I remember correctly, there is only one dynamite and four different spots you can use it at.

And iirc, there are only two available healing items (Three if I count healing pebbles as one and four with the healing staff). First aid kit can be found in mine dungeon, which refreshes every few weeks. Healing powder can be obtained from kobolds, or you can make it on the alchemy bench. Hermit in the swamp area has one in his hut.