From EWR it's $46 plus toll (if any) and tip.

From JFK, it'll definitely be more. The $3.00 initial charge plus mileage alone would be about $47. Add to that $0.40 for each minute stopped/slowed in traffic, an extra $0.40 per 1/5 mile (or minute stopped/slowed in traffic) once you hit the NY/NJ line in the Lincoln Tunnel, up to $1 in time-of-day surcharges, and the $6-8 toll for the cab to get back to Manhattan, not to mention the potential traffic nightmare of driving across Manhattan, and EWR is definitely a better option.