Found hiding in the treasure room. After acquiring 500 diamonds, Scratch will allow you into the Secret Shop, added in update 2.1. You can exchange orbs for icons, colors, and the Master Emblem, providing access to the Chamber of Time. Clicking one of the locks on the icon kit screen will cause him to give you an icon.

Found in the treasure room. After acquiring 200 diamonds, you are allowed access to the Community Shop, added in update 2.11. Unlike the other shop, the icons for sale in this shop are from the icon contest, held by Michigun, Viprin, and Aerma.

Found in the treasure room. After acquiring 1000 diamonds, you are allowed into the Mechanic Shop, added in 2.2. Many new Icons are for sale here, as well as the insert, which allows you to customize menu music and practice music.

Found in the treasure room. After acquiring 2000 diamonds, you are allowed into the diamond shop, added in update 2.2. What separates this shop from the others is that, instead of orbs being the currency, it's diamond shards.