I'd agree with just buying some.
Over the weekend I mined altcoins to trade for BTC.
Have 2 AMD R9 270 cards. I set a CGminer (mining software) so work on the pool at
www.multipool.us. Multipool mines the most profitable altcoin so it switches to what ever is best to mine. It mostly mined Dogecoins but there are about 6 others it mined.
I set up payouts to go right to Cryptsy (
www.cryptsy.com) and autosell for BTC.
so for 3 days of mining I made 0.006 BTC this way. about $2 a day.
This morning I bought 0.1 BTC from coinbase.com for $92 and it is worth $101 at MTgox now. (granted I could not move it out of MTgox as cash without some hefty transfer costs and a lot of time).
So I'd recommend starting by setting up an account at coinbase.com (if you are in the US) go through the process for verification which took me a full month for everything and just buy into some coins.