HELP Exhaust System fell out

Hey me and my friend went out today and grabed a rusted 87 civic dx, for $150 canadian, we tried to boost it and start it, we got it started but it shortly died, anyway thats not the issue, the problem is as we were bushing out of the driveway and onto our driveway we hit a pothole in a construction zone, and the whole frigin muffler came out, we thought oh boy new muffle then half of the other tube also came out that was connected to the muffler so the pipe and the muffler are gone and all rusted. so my question is how much can i get a new muffler and the whole thing done for? in a garage?, or how easy or hard do you think itll be to do it our selves? thnx