money is tight and I'm really interested in mining my own BTC.
If you're interested in mining your own BTC, you'll have to get some decent hardware to do so.
You don't really try to use your bicycle when you're
interested in traveling 300miles per hour, do you?
While (in contrast to 300mph on a bike)
mining your own BTC even works with 5MH/s, it's not really worth the hassle,
you'd probably get more BTC by clicking some of those free-mBTC-links every day without mining at all.