You compared two trains, but there are actually three kinds of trains between Washington, DC and New York:
1) Acela Express (fastest, most expensive and all reserved)
2) Metroliner (almost as fast, almost as expensive, all reserved)
3) Acela Regional or other routes (makes more stops, cheapest, unreserved)
For Washington, DC to Wilmington, DE, the cheap train in coach is $45 one way. Unless you want to leave at a specific time, the cheap train is a good option between D.C. and Wilmington.
DC to NY, the cheap train (coach) is also half the price of Acela Express (business), and it takes about an hour longer:
Acela Express $147
Metroliner $128
cheap trains $108 Business Class, coach $72
[This message has been edited by JS (edited 05-18-2002).]