Where can you save more, with induction cooker or LPG stoves?

According to this blog: http://sustainablog.org/2014/07/energy-efficient-induction-cooking/ Induction cooktops are 90% power efficient than LPG stoves which are only 50% efficient. The comparison is based from how fast the cooker type can heat up or can transfer the heat needed to the pan then eventually to the food you're cooking. And apparently, induction cookers are more eco-friendly as there's a lack of wasted heat unlike the LPG which obviously suggests more. But the thing is, ferromagnetic metal such as cast iron or stainless steel should be present or the main component of the cooking pan you're using. Meaning, since it's a new technology you have no choice but to keep your old pans and other cooking ware. And based from those induction-friendly cookware that I can see in malls, they're a bit pricey.