Speed Sensor Rotor


In the process of changing the front sprocket...I broke a tooth off the speed sensor rotor.
1.Will this only affect the speedo? As my gearing is 16/42 so my speedo is off anyway.
2. Where would be the best place to get another?
3. Anyone know about how much one of those babys cost?

I am getting the my new chain/sprockets this week so it would be nice to know if I need to replace the rotor before I put everything back together.
If your gonna replace it do it now...If you only broke one tooth it may still work can't remember how many it has...About $8 is all that they cost from the dealer...