Wait, int money? Does that imply he spawns like the normal Merchant does, when carrying a certain amount of money?
Also, Chest Seller as an NPC name seems kind of clunky. You could change it to Collector or Hoarder, if you don't mind it being less straightforward (I get it was added for only gameplay reasons and isn't professional, though).
And another suggestion; craftable Water Walking Boots and Lava Charms?
Water Walking boots with something like 30-50 fins (so you do have to grind a fair bit for it but not tediously so), Hermes Boots/equivalents and 10 Water Walking Potions?
Lava Charm with 20 Fire Blossom, 5 Hellstone Bars, 10 Obsidian Skin Potions, an Obsidian Rose, and a Band of Regeneration (turning a bracelet into a necklace somehow lol).