The Plains smelter uses the Ashland ore. I didn't find the iron requirement to be bad, a friend and I knocked out two crypts which took no time and then we smelted it.
Plains mixes things up a bit and uses Black Iron for weapons and Flax for armor, if anything, Plains gear is obtained and upgraded the quickest and with the least amount of hassle compared to the other biomes.
I actually never end up upgrading any of my gear until I reach the plains because the equipment for that biome is so cheap.