I have ordered two MXL 603 mics.
Will these work for miking piano?
How should I position them?
Is there a better way to do if for the same amount of money?
I think in live situations you will run into the problem that only two condenser microphones will not capture the whole range of the piano effectively.
Then again it depends on the musical style:
And of course on the player:
That all being said, I'd suggest you to use an X/Y Stereo approach where the microphones are positioned as close as possible slightly above the player's head, pointed towards the middle region of the strings, because this is where "most" of the sound is coming from.
As your budget is limited, using two condensers is probably the only way to go. Miking pianos is one of the hardest things to do in recording of instruments. In the end I'd just suggest you to experiment and see what fits best. Trust your ears.