Comparison of railroad commuter train fares
Every year, New Jersey Association of Rail Passengers does a price comparison of various trip lengths and the cost of fares and monthly passes.
It shows that the prices for NJ Transit generally are much higher than other high-use systems ("NJ Transit commuters pay the highest fares in the country, analysis finds," Newark Star-Ledger).
Washington-area railroad fares. For longer distances, MARC--the Maryland Railroad Commuter line--is about the cheapest of the major rail lines.
For shorter distances, "intra-suburb," the Metro North service within Connecticut is significantly cheaper than any other service. The MARC shorter distances fares are cheaper than some routes-systems and more expensive than others.
The Virginia Railway Express service wasn't included in the comparisons, but it ranks in the middle--more than MARC, less than NJTransit, comparable to MBTA in Boston.
7-day service shapes higher pricing. Note that most of the systems have 7-day/week service, which increases pricing compared to the DC-area services. VRE doesn't run on weekends, and MARC's weekend service on the Penn Line has been running only since December 2013.