I'm inclined to say "we buy what we need" and move on. As far as "studded" leather goes, I guess the question for the DM is: Do you want us to be able to spend money to give Fern a +1 AC? The way I see it (when it comes to armor) is he'll just be adding some hardened leather vambraces & spaulders and probably a silly-looking leather skullcap to shore up his AC. He probably doesn't need to actually buy a suit of "studded leather" and sell his "leather" armour.
It's probably available, if not here, then certainly at the fort.
BUT, otoh, we've just started. Do we need to raise AC from how the character was built before we even have an encounter? YMMV.