What should i expect to pay at a shop for them to build a 2.5 catback and installing my resonator and muffler(mandrel bent)? I was thinking 50 dollars or so, am i close here?

it depends on the shop.

I paid 125$ for materials,bending and instalation. I went to a local shop that charges an insanley low 25$/hr labor rate though.In my area most non-dealer shops are charging 50 to 70$ An hour. It cost me about 60 in labor and the rest in materials.(piping, clamps, hangers) Plus i tipped him 20$ because he's a friend of the family and he did it for me on a moments notice in front of other appoinments.So it would have been about 105 without the tip.