What should I use for a 3.3 voltage reference that sinks maximum of 1mA?
I don't know that you mean by "precision", but the LT1461CCS8-3.3 is pretty good (0.08% tolerance and 12ppm/°C maximum drift). It's a series reference that can supply 1mA easily. 

If you want cheap, use a TL431 and three resistors (1% + resistor tolerance, 50ppm/°C typical drift).