Just open an account with a broker such as TD ameritrade, scott trade or etrade. put some money in and then place an order for the symbol exbx. Don't buy at market. place a bid of what you are willing to pay for each share. Hope this helps.
Also make sure it is an online account instead of a standard account with Scottrade because on exobox you have to call to place a trade with them because there is not a bid or ask price. To place a trade by phone if you have an online account will be cheaper. Other brokers such as optionsxpress, you do not have to call to place a trade reguardless of a bid or ask. You can do it online just as any other stock you would buy. I am sure just by calling one of them they will be glad to guide you. Just make sure a stated already that you do not do make a market order. Make it a limit order.
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