I'm sitting at EWR right now after having spent a long layover in Manhattan. I've taken various forms of transportation from EWR into the city before---AirTrain/NJ Transit rail combo being one of them---and decided to go the low-budget route today and board the New Jersey Transit #62 bus to Newark Penn Station, connecting to the PATH train. Total cost of the journey: $2.60 one-way/$5.20 round trip, as opposed to $8.30/$16.60 on the AirTrain/PATH or $11.55/$23.10 on the AirTrain/NJ Transit. It took exactly one hour from Terminal A to the 33rd Street PATH station, and around 50 minutes on the return from the World Trade Center PATH station.

Based on my experience today, I can conclude that the #62 is a cheap but still relatively efficient option. It leaves every 15-40 minutes from each terminal; the journey to downtown Newark takes around 20-25 minutes, with a few local stops. PATH from Newark to World Trade Center is only another 22 minutes. The #62 drops you off and picks you up right in the bus lanes at the train station...just a few steps from either NJ Transit or PATH.

On the inbound trip, there were even luggage racks (methinks the bus used on this route must have been equipped for the old "Airlink" service).

So if you're not carrying much luggage, the #62/PATH is the way to go...less than half the price of the AirTrain and not a whole lot longer timewise.