Following the path to Goron City just below Death Mountain in the Eldin region, you will eventually come across a group of goron miners and a hylian who needs your services. In exchange for 10 fireproof lizards, he offers to give you his anti-flame stone armor. To get them, simply stay in the area and lift all the stones, hurrying to press the right button to catch them right after. In 5 minutes you should have obtained a sufficient number of lizards.
Helm and boots
Go to Goron Village's clothing store, you should find your happiness there in exchange, of course, for several hundred rubies. In total, this should cost you nearly 2700 rubies.
Written by Bastien "Lloyd" Dubosq-Luyer. Translated from French by Millenium.us.org.