Is raynaud's disease pretty rare?

No, not rare: Raynaud's disease (no cause found) and raynaud's syndrome (caused by another medical condition) are not that rare. An estimated 3% to 5% of the population have raynaud's phenomenon, although symptoms can range from quite mild all the way to severe.

No: It's actually quite common but many times is not bad enough to cause people to seek medical attention so they may not know they have it.