I was wondering if a pair of good 'ol SM57s would work to start out with. They are a very versatile mic that sees a lot of use on guitar amps and things. Not to mention they are only $99 apiece at Sweetwater. I'd rather not break the bank until I have more experience.
Horowitzian, anything will work when starting out. However, You won't be happy with a SM57 in the long run - it's not as sensitive, it has frequency peaks in the mids, and lacks air in the highs, and is deficient in the bass. The SM57 is a dynamic mic. You really should have condenser mics in your arsenal.
Dynamic and condenser mics differ in how they produce an electrical signals going into your recorder:Dynamic mics
use a diaphragm attached to a moving-coil in a magnetic field to generate a signal in the presence of sound vibration, just like a speaker working in reverse. The mass of the moving coil results in a relatively poor transient response and less sensitivity than a condenser mic. They are better suited for louder sources like in guitar amps or drums where they don't distort as much as condensers in high SPL situations.Condenser mics
have a very thin plastic diaphragm coated with gold/nickel, mounted very close to a conductive back plate, which forms a collective unit called a capacitor or condenser. A polarizing voltage feeds through the capacitor by an external power supply, e.g. Microtrack II's 48V "phantom power." Sound causes the diaphragm to vibrate: as the diaphragm moves closer to the back plate, there is an increase capacitance which results in a discharge of current, when the diaphragm moves away from the back plate, there is a decrease in the capacitance which results in a discharge of current. This cycle produces an electrical signal going to the recorder. Condensers are better suited to capture nuances, wider frequency response, and transients due to their increased sensitivity over dynamic mics.
Avoid the temptation with less expensive Chinese mics (Studio Projects, Samson, Rode, MXL, etc.). I find them to sound brittle, harsh, lack a full body bass, and are not as reliable. You don't need Neumann either. I'd save up for the U.S. made Shure KSM141. At $800, you're essentially getting a pair of omni and cardiod mics all in one package. I've looked all over... It's going to be difficult to find a pair of quality condensers that are as neutral or as classy in sound as the Shure for that price. Like I previously mentioned, these are Schoeps clones, which are standard in high end classical piano recording studios. The Schoeps omni and cardiod capsules with the amplifier body will cost $5525.
I hope some of these ideas and concepts help... I hope you capture the best sound from your piano! Good Luck and keep me posted!