Im not certain how youall are gaging your tanks but here a 125 lb oxygen tank refill is $14 A 200 is $21. and I use the little grill propaine tanks cause they are easy for me to move they are $17 exchange here.

just consider this being new at cutting or cheep equipment can cost you $20 to $30 a ton to cut . Find a torch man and have him help you learn how to adjust your flame for what gas and what metal, it will save you big bucks even if you have to pay him for the lessons. I dont think It can really be done here because it is done by sight and sound.