I have compiled a list of sources for the elements that are available to the amateur chemist. Indium will be discussed here.
Indium is an extremely soft, silver-gray metal. It is found under aluminium in the post-transition metal area. Indium is moderatley reactive and dissolves with ease in strong acids. Its oxide is amphoteric, meaning that it is soluble in both acids and bases. Indium compounds are colorless or white and acidic, making them uninteresting. Indium metal, however, is extremely malleable and retains this characteristic to cryogenic temperatures. Indium can be used to seal gaps because of its tendency to stick to other metals, acting like a superior form of paraffin wax. Indium metal is quite expensive, with a current price of about 250 USD per pound.
In element form: Galinstan, a liquid metal alloy used in Geratherm mercury-free fever thermometers, contains about 32% indium. Indium is often used in specialty solders. Field's metal, used in some low-melting seals for fire sprinkler systems, contains indium. The brass pin in the center of AA or AAA alkaline batteries is often plated with indium to prevent the zinc from passivation.
In compound form: LCD screens use indium tin oxide (90% indium oxide) for transparent electrodes. Indium is found in most LEDs.
Here is my sample of indium. It is a piece of pure indium metal from GalliumSource LLC. This is only a small piece, flattened to a foil by gentle pressure.