Keeping a healthy weight, exercise, and limiting back stress is very important. I have my boy on Glucosamine/chondroitin/msm because he has luxating patella and dislocated a knee at one point.
I know one woman with a 13year old dachshund who never had a back issue and was never limited with jumping on and off couches, but had limited stair access (the dog came from a good Austrian breeder). Many other people I had spoke to who had older dachshunds or past dachshunds did speak of back issues. I won't take Leo off his supplements ever and he gets a good exercise every day and has limited stair access so all we can do his hope he does not have any strong genetic predisposition to IVDD.
If you choose to buy a doxie it should be a very good reputable breeder without evidence of back issues in the lines. These dogs are not the kind to pick up from back yard breeders who "love the breed" and think their dog is so cute they let it have puppies. Temperament,health and wellness should take precedence over all else! If you are going to get an unknown always check for rescues first!