Also it seems padded armour costs more than leather? Such as the chest piece which is ten compared to the leather which is 4. Or was it 5? Same difference though.
That's correct. Since they have the same armor value, leather (being higher tech) is just cheaper. I do expect it's easier to cut a hunk of leather, strap it to a mold, and boil it than it is to sew an entire set of armor, after all 
