Sourcing CO2 in a Tank

Many years ago I enjoyed using a SodaStream. Then I stopped. Recently I bought something similar and got hooked again. I would like to get back to this in Mexico. It would be so much more convenient than lugging heavy bottles of soft drinks around.

I brought a couple of empty SodaStream canisters to Mexico. Now I am looking for equipment to refill them. It is easy to get the tubing and valves to refill the SS cartridges. Now I am looking for how to supply the CO2.

In Canada, a common process is to buy the CO2 in a CO2 siphon tank, then exchange the tank for a full one when it is empty. I understand that in the US it is common to buy a CO2 siphon tank and have that tank refilled as needed.

Does anyone know how to buy food grade CO2 in siphon canister in the Zihuatanejo area?