Induction vs. propane gas expense?
Some approximate figures

Energy efficiency while cooking


Induction 90%
Electric resistive 55%
Gas 50%


Energy efficiency while heating up


Induction 99%
Electric resistive 0%
Gas 0%


Time, total energy used, and cost to boil 2 l of Water


Induction 2:20, 0.2 kWh, $0.034
Electric resistive 5:00, 0.34 kWh, $0.058
Gas 4:00, 0.37 kWh, $0.016


Assumptions

Gas burner is clean and correctly adjusted

Costs are estimates based on USA high prices as of 2013

In many other countries gas will be much more expensive

Bottled gas will be nearly twice the gas price from town supply gas