The $36 ticket is now the $41 ticket. This is the 14-day advance purchase fare. For a daily or almost daily commute, there are really two options. The economy(?) way is the SEPTA/NJT combo. You would need a monthly SEPTA "Anywhere" pass ($191) plus a monthly NJ Transit Trenton to New York pass ($440). That brings you to $631 a month. Of course, the downside is that it is a long ride, time wise, and your in a commuter train with commuter train seating all the way.
The high price option is the Amtrak monthly pass at $1386, plus whichever SEPTA pass you need to get to 30th Street. The benefit is a much faster and more comfortable ride on Amtrak compared to the two-train ride on SEPTA/NJT. Plus, you get at-seat power and internet access, which could be of some advantage for checking email and maybe even getting some work done en route. Amtrak monthly passes are accepted on most non-Acela trains with no advance reservations. The ability to vary your schedule without impacting train reservations is a benefit of the Amtrak monthly pass as compared to simply reserving trains one at a time.
Depending on where you are in the western burbs, the Amtrak monthly option is also available from Ardmore and Paoli ($1458) and Exton ($1476). This limits you to using only Amtrak Keystone trains west of 30th Street, but it saves you the SEPTA pass, and it gives you a one-seat ride all the way to New York. Ardmore and Exton only have certain Amtrak Keystone trains stop. All Keystone trains stop at Paoli.
The bottom line is that there is no cheap way to make a 200-mile round trip commute to New York from the Philly area. There's the expensive way, SEPTA/NJT, that is slow and kind of a pain, and there is the real expensive way, Amtrak, that is at least faster and much more comfortable.