While the Flyback transformers can be salvaged from old/damaged TVs, they prove to be rare components, and finding a quality Flyback secondary is often a great challenge.
On the other hand, a good Flyback secondary can get easily destroyed , it the voltage level inside gets too high (the insulation is punctured internally).
This is why I’ve decided to build one with proper insulation from scratch, since the whole thing is merely a multi-layer coil. Using 0.2mm CuEm wire and a PVC pipe for supporting the coil, I’ve created a 2500 turns flyback. The winding was deployed on multiple layer, insulated with PVC tape.
This video shows a test run with this flyback secondary. Bottom line, I encourage you to try making your own Flybacks, since it’s quite easy. More on the ZVS driver here.