It’s good that you’re interested in building capital through investments, that sort of attitude is what will help get our economy out of this slump. What might be hard to hear is that you won’t be able to see much gains if you continually buy a hundred dollars worth of stock every month as the commission you have to pay over online brokerages will often cost you about $10 dollars per trade which is already 10% of what you’re investing.

On top of that most brokerages will charge you monthly fees and occasionally yearly fees. Chances of seeing 10% returns in this market will be tough unless you’re playing the inverse ETF game but that will only increase the risk as the market is very volatile right now because of low actual traded volume.

Gold will never be a good investment if you’re buying in small quantities. In order for an investor to see any substantial growth it would have to be in values of $200,000+ as no one will pay for the tiny fluctuations on a $800 1 ounce gold bullion.

If you really want to start buying stock I recommend saving up the money month after month and buying in bulk. $500 – $1000 dollar increments are safe and you will be able to see slight changes from month to month which can be very exciting for new investors. Some online brokerages I recommend are TD Ameritrade, E*Trade, Charles Schwab, and Sharebuilder. I prefer Sharebuilder as their is no yearly/monthly fees, only a commission on each trade.

The safest and probably financially smartest to do right now though is put it all in a savings account to hold onto for a rainy day (or downsizing). This way you can rack up a tiny bit of interest depending on how long you keep it in there.

Edit: Oh I missed the part where you said that you’re 17. If you’re in it for the long run then I definitely recommend you save up your money so you can invest in bulk. You’ll probably be tempted to buy something else but don’t! Consider it as a good learning experience.

Just remember to keep this in mind for the rest of your life: don’t invest with borrowed money (buying on margin) and don’t invest more than you can afford. You have to be okay with losing the entire amount you invest otherwise it’s too much that you’re risking. Brokers will tell you otherwise but that’s only because it’s not their money.

The ETF GLD which follows gold pretty closely will make it possible to do this. If you want to take a risk on gold you might consider to buy insurance on it. You could buy a put at the money per every 100 shares a month or so out. If gold drops you can cash in your insurance and buy more shares and re-insure with the insurance payout at the new lower price. But I think gold is not so good. Besides golds long term performance is really bad. Put a calendar spread on QQQQ and adjust as needed. You will need to save some cash up before you can do this but it is more safe than gold. If you want to buy and hold a commodities fund might work out.
* Oppenheimer Real Asset Fund
* PIMCO Commodity Real Return Strategy
* Goldman Sachs Commodities Index
* Deutsche Bank Liquid Commodities Index
* Rogers International Commodities Index
* Dow Jones AIG Commodities Index

Depends on your time horizon and risk tolerance. If you’re looking long term and don’t mind the risk, consider buying shares of a no load mutual fund.

If you’re a short term investor, then you might want to consider a money market account.