Depending on the amount your broker requires for margin, you can start
trading with an amount as low as $500. Remember that starting out with
low trading capital may put you at disadvantage because you will only
be able to trade forex in small share lot sizes.
Howerver, don't wait until you have hundreds of thousands of dollars.
First, trade a demo account or two (or three) until you are
comfortable with the platform and can show at least some signs of
being profitable. Then open an account with a broker that lets you
trade microlots or nanolots. This will let you get live trading
experience with less than $500 at risk