The NCR18650B has about 5A CDR, they are far from ideal but better than the Ultrafires. There is the concern that the turbo may trip the the over current protection. If the recommended sources don’t ship to your undisclosed location, maybe your country or a near country has vape shops or dedicated flashlight shops that sell good batteries. I think protected batteries are not really needed, good quality unprotected batteries with high CDR should be safe enough. If the nitecores are flat top they are 99% sure unprotected, if you have 4 of them maybe you can post a picture or a link so we can find the CDR. Some people use adapters or small neodymium magnets to adapt flat top batteries.
I think you posted a link with prices in South African currency so maybe they can ship to your country? This shop was recommended in a thread for SA customers, maybe they can ship to you too? but you may need to buy some cheap flashlight from there too. The 18650 prices are expensive if the currency conversion is correct, that’s unfortunately the reality of living outside the first world.
Does anyone know precisely what current is required for the MT40?
Edit: did you check this thread first Massive post on where to get lithium-ion batteries everywhere in the world! Look at Post 2-5 for info, And Canada Post 123 ?
Edit2: Ilumn ships to SA for $31 (cape town zip code) so they may ship to your country too, but of course that’s shipping, not import taxes. Also check http://www.international.mtnelectronics.com/