This is an easily searchable question, check out this page which outlines alk your travel options: https://www.tripsavvy.com/getting-from-nyc-to-philadelphia-1613035 Amtrak is fast (about 1.5 hours) but extensive ($39-$179 each way) vs. NJT to Trenton where you would transfer to the SEPTA train the rest of the way (takes about 2.5 hours total) but it's cheaper (about $20)
Less than $40 round trip on NJT...Amtrak will be double and in some cases triple that amount. Greyhound is also an option & prices vary.
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