Unfortunately, if a professional data recovery service is not able to recover anything from your 1TB Samsung SSD, there are no other choices left for you. And you are not likely to recover your data from the SSD by using any third-party data recovery software.
I think you should let them try to repair your SSD, even if it costs $1500. Also, you can send your Samsung SSD to another professional data recovery service and see if you can cost less to get both the SSD repaired and your data recovered.
According to your description, your SSD is physically damaged, right? Otherwise, the service center you send it to would not attempt to a repair. Part of the explanation for the price they offer is the relatively low success rate. If the guy is going to put several hours into an experimental repair, with no guarantee that it will work, then that's baked into the price.
The odds are, he will spend many hours working on repairing your SSD and get paid $0 for the unrecoverable case. So $1500 is a fair bid to me.