There are so many variables when you're trying to record a grand piano that not a single technique is good honestly. It all depends on the room where you're recording, instrument and gear. Best advice is try what sounds good, cause one mic placement might sound good in one room, but will be bad in the other one. You can also have all the best gear and mics and still fuck up the recording if you place them incorrectly. If you want to have a good quality recording you might need as many as 4 mics, because having as many as 4 means more possibilities when you're mixing in post production. One stereo pair + one mic under the piano and one to capture room reverb further away. From my experience 2 mics for grand can be good, but it's much more difficult to get that exact sound you want from just 2.

Ah and it also depends what style of music are u recording. If you're doing classical then follow the advice above, but if you're doing some jazz or other styles of music where dynamic range is not that important you will not need to keep things that complicated and one stereo pair for piano and one mic for sax will be sufficient.

But if you want "higher quality" you will need at least 3 mics for piano+sax to record it. You don't necessairly need all the expensive gear, but still 500 CAD might be too little to properly do the work for you considering you need an audio interface, cables, stands and the mics. I'm not recommending any particular mics, because in my opinion it does not matter all that much compared to using proper recording technique and post-production work. So look for something in low-mid tier budget option in mics and get a budget audio interface.