The 1889 Silver Dollar is a very common coin, with literally tens of thousands of certified Mint State examples available. Thousands of MS65 examples have been certified by PCGS, as have hundreds of MS66 and better examples. Where this date gets really rare is at the MS67 level. The finest example is a single PCGS MS68.
Cameo and Deep Cameo examples represent a mere fraction of the total population, but they are still readily available in the market. Both Cameo and Deep Cameo examples can be found up through MS66, but no further.