Just an echo of what they said. I've spent years studying, learning, reading etc and had my first serious session last saturday. Because I've spent so much time learning the theory, understaning what to look for with mic placement, phase, etc....I was actually able to get some really good sounds. Now, it took a lot of work and some creativity to work around my limited gear but you can do it.
Remember that if it sounds good at the source then you are ahead of most of the young "I want to record at home" crowd. Move your piano around the room (as best as you can) see where it sounds best. If you are recording an upright piano I highly reccomend reading the Sound on Sound article on how to do it effectively.
So in short: yes great recordings can be on crap gear...it just takes work. But also remember....honesty translates. If the musicians are tallented and passionate....a decent recording will sound better to most people than an exquisite recording of lack-luster performances.
Some final thoughts:
1. Keep your expectations realistic
2. PLAN!!! Know what mics/inputs/instruments will be used where and how.
3. Semper Gumbi (look it up)
4. Have fun!!! So many times we forget about this. Music is fun. Recording is fun. Don't stress. You are obviously not doing this as a profession yet, so enjoy it and learn from everything, especially your mistakes.
5. Take honest stock of the sounds you are getting. (I moved my piano mics from a spaced pair to an X/Y array....my low end turned to mush.....So I moved it back.) If somethings not working, no matter how cool you think it is, or what producer or engineer swears by the technique, move to something else.
6. Re-evaluate you plan (See #3)
7. Have fun
Let us know how thing turn out!