Despite what the Slayer's armor looks like it is Light armor.  The base of the armor is Leather to keep it tight and flexible for tight spaces that are then reinforced by chain mail and small pieces of steel plate around the front and back.  As a bonus non of the metal parts touch your skin.  All the steel pieces are upgrade-able when better metals are available. 

(The AC is 14+Dex modifier.  The price should probably be no more then 50gp)

The breastplate and shoulder protectors of this armor are made of leather that has been stiffened by being boiled in oil. The rest of the armor is made of softer and more flexible materials.