My experience has been that you can often find the screw in canisters in trade type shops, I once in Denmark couldn't find any canisters for a gas stove until I found a gas canister for a blowtorch, exactly the same fitting. Had to hold the pot all the time so it didn't fall over cos the canister was about 80mm wife by 200mm high. Worked fine though. Also in Patagonia in Chile I found it fairly easy to find screw in gas canisters