Save my tooth?

My dentist recommends the removal of a molar, number 45. It broke about 13 years ago, was filled, required a root canal about a year later and was then filled again, was re-filled with a post about 3 years ago (this was done in the Netherlands, where they said I could continue with a new filling for another number of years before putting in a crown; I have moved back to Canada since). Now however (after pregnancy), X-rays show that it has a lot of extra decay (from the sides), and the dentist reckons there is nothing that can be done to save the tooth and crown it, and that it needs to come out. At the same time, they are telling me to get a bone graft done immediately as well, and getting a denture, as well as having me agree to an implant in about a year’s time (as she says that waiting any longer will most likely lead to too much bone loss). My dentist insists that if I don\'t do all of this right now, I risk loosing the bone, and might not be able to get an implant later. I expressed my concern at the financial part of all of this (an estimated cost of CAD$5500), given that I am a grad student with a small child, and asked what the consequences are if I didn\'t go ahead with all of this, but beyond an \'if you don\'t do this now, you might loose your opportunity forever\', I didn\'t get an answer. As I don\'t have this kind of money at the moment and I am not in a lot of pain so there is no great urgency, I am wondering what my options are: 1) Are there things I should have my dentist investigate before extracting the tooth (i.e. another root canal, refilling, seeing if a crown is still a possibility) or is that, as the dentist says, a waste of money? 2) Is a bone graft and implant right now really necessary? What happens if I wait? The dentist said it was a medical necessity that unfortunately isn\'t covered by any insurance, but I am still not sure if I understand why. What are the (medical) consequences of loosing a tooth and not going forward with bone graft and implant right away? Does the bone loss imply a risk of my jaw snapping in two? Or is it merely a cosmetic issue?