I record a lot at home and use a cheap AT mic straight into the interface. I tend to get a pretty good sound most of the time. They key is to "how" you mic the guitar. Each acoustic instrument has a "sweet" spot where you can find the truest tone of the guitar ring through the wood. The key is to mic it so that sustain comes through and you capture the best possible sound from your instrument acoustically. Try playing an open chord, and while it is ringing move it the guitar around the mic and see what sounds comes out the best. Make sure to check your mic for any switches that may be on (low cut, phase switches, etc.) Also, what type of interface are you using? This makes a difference. You also have to think about how you mix the acoustic and what your EQ, compression, reverb settings you use.

A true gem in recording acoustic guitar is doubling every part your record. This is very, very common and you can do this by playing the same part twice and than pan one track L and the other track R. This really helps get a great sound with minimal equipment.

Best of luck and let me know if you any other questions.