One of the cheapest and most reputable out there at the moment is Fidelity, another one with a little higher costs is Vanguard. If you are in a country outside of the US in which Fidelity and Vanguard don’t have any offerings, one of the cheapest brokers that might be available is Interactive Brokers. Interactive Brokers has however a monthly minimum activity fee, you have to be aware of, and is a little more difficult to handle than Fidelity and Vanguard.

On a small budget, Fidelity is the clear choice to go, due to their no minimum investment funds.