any suggestions of affordable exhaust for an 850 and a ballpark price

Is this for an NA or Turbo model?

If it is an NA 850 I suggest a 2.25" to 2.5" catback exhaust with a Flowmaster muffler.

If it is a Turbo model 850 I suggest a 3" mandrel bent downpipe to a 2.5" mandrel bent catback with a Magnaflow muffler.

A local muffler shop that can mandrel bend is where I would go. You shouldn't pay over $350 for the NA catback I suggested and you shouldn't pay over $800 for the Turbo system I suggested.