In-built stove (countertop with 2 burners) or camping stove - what is cheaper in terms of gas cartridges / tank

Hey you all! Nice to meet you :)

We have just bought a lovely camper van in Chile (thank you guys from Laybacktravel - you guys rock!) and are doing some changes to the interior / lay-out. We first wanted to install a stove with 2 burners (encimera) and buy a 5kg gas bottle and design our furniture in a way that it is secure to travel. However, someone here in the town we are in opined that a gas bottle of 5kg would last us about 20 days. The bottle costs about 17 000 -- to fill up with gas another 7000.-. The stove would be about 90 000 new.