In Skyward Sword, Link can purchase the Small Quiver from the Gear Shop for 150 Rupees. It can be placed in his Adventure Pouch. It allows Link to carry 5 extra Arrows which he can use with the Bow. It will not appear in the Gear Shop until Link has completed the Sandship.
The Small Quiver can be upgraded at the Scrap Shop. The first upgrade is the Medium Quiver, which can hold 10 extra arrows. It requires 5 Amber Relics, 3 Dusk Relics, and 3 Monster Horns to upgrade. The cost is 50 Rupees. The second and final upgrade is the Large Quiver, which can hold 15 extra arrows. It requires 3 Dusk Relics, 2 Monster Horns, 1 Goddess Plume, and 1 Golden Skull to upgrade. The cost of this upgrade is 100 Rupees.