I mentioned this to a youtuber worried on the same problem, with tin being "so expensive"
once you get your first tin ingot - Progression becomes loads easier.
for one - Grips and guards - These are the primary grind in copper
If you didn't have to spend a fair bit on pole grips, or on both grips and guards - copper wouldn't likely be quite as slow - at copper, you're basically paying for both parts out of pocket, and relying on both to get you results.
but at tin, You're relying solely on Tin, as you will be in every other tier
Additionally, you won't struggle with stock as much after tin either, as you'll always be able to ring out a stack of copper to fill an order in a pinch, and grips and guards are a fraction of a higher-tier's ingot price - meaning more sales, meaning more spare change for misc, and more exp for more (I'd go with charisma honestly, it'll eventually mean a whole stack of a tier down in bonus funds, and that, gets you good stock/reserves.) stats
But yeah - Coppers main detractors are that its all you can use in terms of ingots, grips and guards rival its price, and you need both with every sale, and mark up is only 10%, and some change.
10% of tin is 5 copper ingots, just off the bat (500-> 550)
Or its a replacement rare grip and guard, along side the tin spent
the one tin, pays for the entire weapon - rather than the one copper, and its grip, and its guard, barely paying for itself.
And when you get to 1 ingot of the next tier, take a moment to look at your options.
if there's no ore for that tier, focus on fulfilling customer demands for those ingots, and reap the immediate replacement of them and slowly but much more steadily, climb to two ingots, then 3, then awhole stock full
Then 1 ingot of the next tier, rapidly builds to two, eventually it'll start rapidly building to three -and once again, check for ore There's no point in upgrading your hammer or pick if there's no use to be garnered from it, but on the flip side, you'll get an immediate, drastic boost if you can get to the pick, and there's 2+ veins waiting for you to plunder.