Very little. Realistically, low-tier items should either see a natural increase in price, or the mythicals should sell for cheap.
In Unturned’s case, there’s an overabundance of commons and uncommons because of all the weapons that can be skinned, and the amount of camo/solid patterns. They’d all stay at relatively the same price as they are now (3 to 5 cents) as the supply is still quite high, and is the easiest to replenish.
Additionally, assuming you’re spending crafting materials to generate a specific rarity immediately, rather than using a “Mythifier Tool” on a specific item, the mythicals are going to sell cheap. There is less value in a specific mythical on a specific item, because there’s less demand. A “Mythifier Tool” is more valuable because that aspect of choice makes the item for generalized and thus versatile, so there’s higher demand.
So, very little profit.