Investors who use a cash account have to pay the full amount for any investments purchased. Thus, if you want to buy $5,000 of stock, you’ll have to have $5,000 in your account (plus any commissions to place the trade). Some brokers automatically sign up customers for a cash account, and “upgrade” Trades at TD Ameritrade cost $6.95 per trade plus $0.75 cents per contract. There is no account minimum. The site offers a current promotion where you get 60 days of commission-free equity, ETF, and options trades with a deposit of $3,000 or more. You get additional bonuses with larger opening deposits. No minimum to open an account: $0 commissions on online stock and ETF trades: TradeStation: Stocks: No minimum requirement ($2,000 for a Margin Account) Commission-Free Trades on Stocks, ETFs