i picked mining up later in the game as a skill to get mats for alts and as a gathering skill for later on, i figured i would be able to power lvl it by just buying ore and smelting, but it seems my smelting skills go grey b4 i get to the next ore on skill to smelt, so would i have to invest time in actually searching for ore or is there a different way to lvl it up?

invest your time like the rest of us

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Yup.  You're screwed.

the only way to increase the skill is to actually mine veins

Not exactly true 100% of the time.  You can get skill levels purely by smelting.  But you can't go the entire way, as there are 'dead areas' between levels in which smelting will give no skill ups.

Go farm some tin.  It'll do your legs some good.