I would not recommend that. You should at least buy $100 worth of Bitcoins.
Bitcoin isn’t something that you can buy next store i.e; pay a visit, handover cash and you should have your Bitcoins.
To buy Bitcoins with Fiat there are three methods:
Buy with Credit Card - You can buy Bitcoin, Litecoin, Ethereum at Coinbase - The best option for users coming from United States and Europe and many other countries with $10 BONUS on a purchase of $100. You can also use CEX.IO, Coinmama for their easy to sue Credit card options. They usually charge ±7% other exchanges are pretty much expensive.
Bank account (Bank wire) - You can use exchanges like Coinbase, bitstamp and bittrex to make a transfer/wire from your bank account and make a purchase of your favorite Crypto. But remember, most exchanges such as bittrex provides this facility to those willing to invest at least $10,000.
Individuals - Find individuals like me, handover cash (if nearby) and make a purchase with Fiat.
Why should you not buy small amounts?
Bitcoin transaction fees currently stands at $5+. I just made a $10 transaction and paid $5.32 as fees. Meaning that I received only $4.68 which is ridiculous.
Bitcoin fees are at it’s peak these days and will remain so for a while.
Now imagine you are making a $10 buy from CEX.IO or Coinmama with your credit card. Here’s how it should go.
Bought $10 bitcoin.
Exchange fees: 10 x 7% (at min)= $0.7
Visa/Master card fees: No idea.
Forex Mark-up: 3.5% (last time charged by my bank. Applies only if you have other than USD currency)
BTC transaction fees: $5+
Just in case you want to make a transfer from exchange you won’t even be able to do so. So, why try smaller amounts? I don’t see any reason why you should go for the smaller volume purchases.