I need help with my floor! plz

I am buying a 89 crx I dont know anything else about it yet first I wanted to ask. The floor needs to be replaced is their a bodyshop in toronto that can fix this problem or is it easy enough for me to attempt to do it myself. I tried looking for prefabricated floors for it but have turned up nothing. Also I have just purchased a welder and am thinking of just welding a steel sheet in place of the floor. Is their anything you can do to point me in the best direction of keepin the cost efficient. ANYTHING is helpful...thanks a million