Hi Studio7Records
Good luck and good fortune. I wish you well.
One thing occurred to me that costs nothing and is a short term and very partial solution.
Dropbox is a free app which can be found at dropbox.com (I have no financial or other interest in this or any other product). Dropbox is very popular with Apple and Windows' users. Sign up for free and Dropbox will open on your Mac. It creates a folder found via the toolbar. You can copy (NB copy) any vital files, pictures, PowerPoint presentations etc into the Dropbox Folder and it stores it online. If you had another Apple or Windows device, you could also sync the Dropbox Folder with that device.
In your case, it would represent an incomplete online backup. Moreover, you can access Dropbox from any computer in the world using your username & password. This would allow you to work on projects from any computer knowing that any changes you made would be sync'd to your Mac.
In view of what I assume is a large amount of valuable data on your Mac, you would have to be very selective in what you stored in Dropbox or be prepared to pay for space over and above that which is provided free.
Clearly, you will appreciate that this is no substitute for a total backup on to a EHD; but in your special & financially restricted circumstances, it offers a free, but limited backup option.
Everybody who has contributed so far has done so out of genuinely concerned interest in your problem, based on their (and my) experience of the capricious nature of all drives, whoever makes them.
Lastly, in relation to your last question, it is rumoured that a new iMac may, just may, be in the pipeline for release sometime in the autumn (fall). Under your circumstances, this seems unlikely to be of any immediacy to you.
Once again, I hope you do not meet any misfortune with your precious data.
Ian