This is why I am buying a couple of LTO 6 tapes. Thus far I've been able to buy 4 for approx 120 EUR, 2,5 TB each. They have been around 30 EUR each the past years, and still are approx such price (leaning towards 35 EUR though). I bought a second hand drive for about 500 EUR, and a HBA for it.

Tapes are great for true cold storage (will easily last many decades!) but they will wear out significantly with more intense use: you only get a couple hundred passes total over their full data capacity, either read or write. In practice, you still need plenty of big hard disks to act as nearline storage for practical use, and the tape only rarely does storage and retrieval in bulk. This is also why you see mechanical tape libraries with tens or hundreds of tapes for a single read/write unit: you don't really need more than that.