Merchant

The Merchant class, specializing in farming and money generation, offers many skills to achieve those aims. From being able to improve buy and sell prices to and from NPC shops, all the way to a spelunker buff, and even setting up a shop stall on multiplayer servers.

Unfortunately, they gain only one attack skill which costs coin to use and has a relatively long cooldown. They are best suited to getting geared up and supporting costly gear for large parties.

The quest to become a merchant starts at level 10 from the Merchant. The quest is 2 parts. Acquire 1 gold coin and move out west.

1: Discount does not stack with Discount Card, however it does allow a merchant to sell items (such as the Terra Blade) for 24 gold, while purchasing them back to only 15.4 gold, allowing infinite profit to be made. The largest profit I've found comes from 99 Life Fruits, which sell and rebuy for about 50 Gold profit per stack. This applies to every item you sell, as the discount is applied to the repurchase price, which was originally your sale price.

2: Coin Speciality, oddly enough, seems to work on Statue mobs on occasion, allowing infinite AFK money generation.

3: Toss Coin launches ten silver coins in a random spread (largest seen about 60 degrees between outer projectiles). Unlike other attack skills, the damage does not appear to be altered by equipped weapon, but the damage does appear to be Melee (tested with X Emblems) and can be boosted by the standard means. Even at its highest level and boosted as high as possible, it's not worth using against hard mode monsters.

The Merchant, like the Fisherman class, is arguably best suited to an alt. Even at medium levels the Merchant can be used as an infinite money generator by simply sell/buy cycling a single item stack ad nauseam, and they don't really offer anything more after that asides from infinite Scavenger's Eye.

Since the Merchant is only 5 skill points short of maxing out its entire skill tree at max level, a guide is largely unnecessary, just upgrade Merchant's Eye when you've nowhere else for your points and raise your gamebreaking Discount/Overcharge skills as early as possible.

Final status bonus Update from Arendeth here is info I gathered for N Terraria 6 for the merchant

Max level 30 note for stats use a warrior like build of str and vit Coin Power Description: you gain different bonuses based on their coins, and stack coin slots. Only valid to coins in the coin slot. Type:Passive max points 10

Axe Mastery Description:Turns Part of the weapon's (sic) axe power into damage. Intial Boast as 12% percent adds(sic) 3 percent more boost per skill level.

Open store: 1 point given free after getting coin power to rank 5 description you can open a store to sell to players

Backpack mastery Description:You may use an alternative way of stashing items. Increases            info: acts as portable bag/chest like safe and Discount Makes Shop prices fall 2% decrease per skill level max 10

Makes shop items cost more. overcharge Bonus 2 coin per skill level max 10 needs discount at 5

Coin Mastery Throws Several Coins to cause general damage 15s cooldown?

for class next recommend the warrior from the guide after maxed to class level 30

Raccoon Trivia
Wait, the Merchant class only has skills related to golds, finding treasures and and messing with the shop prices? Who would play with this class, since there are better classes to choose at this tier?

I say that I would. And actually, I played as that class mostly during the mod development, or even gameplays on multiplayer. Don't get it on the wrong side, but I don't really care in Terraria for making use of skills over the time, so most likelly I deal with the game challenges with whatever is in my character hands.

And also because looking for ores, life crystals and chests in the game is a bit annoying.