Not only do you have to be 68+/100k GP for this you also have to be Artisan Goldsmith. If your 68-70 and don't see it to purchase turn in mythril breast plate to rank up to artisan and it should show up....happened to me this morning ^^
You need to be level 68+ in goldsmithing in order to be able to buy this apron, and you need to have 100,000 guild points to buy it.
In order to get guild point you need to trade many of a same item, the item changes every Real Life Day. You can only get a certain amount of guild points per day so this could take a long tims :/
To obtain these items, you must be a novice or greater in your particular craft. Trade your crafted items to the aproned individual, and you will recieve guild points.
Anyone have any clue what you are supposed to make and who you give them to? I tried giving everyone in the guild something from goldsmithing but I was told that you have to give them something they are asking for. I have an idea of what should be done but I haven't tried yet. I'll get back to you on it.