Dachshund IVDD surgery costs what all canine spinal surgery costs in Australia: commonly $5,000 to $15,000 all in, with the typical capital city referral pathway of MRI, hemilaminectomy and hospital care landing between $10,000 and $15,000, and a budget surgical option existing around $5,000.
Dachshunds are the headline breed because their disc disease is baked into the breed's genetics: their discs harden and rupture young, commonly between three and seven years old, and a large share of dachshunds have at least one disc episode in their lifetime. Owning the breed means this number can arrive at any time, which is why the insurance conversation belongs at puppy age, before anything enters the clinical record.
Two dachshund specific notes: recurrence at another disc is a real phenomenon, so ask any quoting surgeon whether preventive fenestration of neighbouring discs is included; and mild first episodes managed with genuine crate rest do well often enough that a pain only dachshund is not an automatic surgical case.
Send what your vet said and quoted. A veterinary surgeon reads it and comes back to you with what they can do and what it would cost, before you pay anything. A written second opinion is from $250.
Send the case, hear back from a surgeon with what they can do and what it costs, and only pay if you go ahead.