If it is a pin-on bucket, you probably don't have much choice but to find the original. If you are able to fabricate, it is more likely you will find a bucket from something else, and then you will have to cut/weld your brackets on it. An even better route would be to make/buy a ssqa (skid-steer quick attach) bracket for your loader arms... that way you can use any skid-steer bucket, and it also opens you up to world of attachments.
I also think there are places out there (everything attachments may be one of them) that will custom build you a bucket if you give them the specs of yours. Look around, there are probably other fabrication places in your area that will either build you a bucket or modify one to work.