That looks like a heavy duty torch.
I think the cheapest way for you to go about this is a oxy + propane setup. You can sub the oxy for an oxygen concentrator if you want. Propane is a cleaner gas to work with / less dangerous / doesn’t create soot. It doesn’t get as hot, but I’ve been using it problem free for 3 years now. I think a lot of other builders use propane over acetylene too.
I find a normal user-owned Prax-Air oxygen tank lasts 3-4 frames total. If you’re just doing brazeons and the occasional dropout, the tank will last you a while. At my local Prax-Air the tank refill is $65 Canadian.
I use a Smith brazing torch. I can’t remember the model, but I have a bunch of tips and switch depending on what I’m doing (silver vs bronze vs fillets vs whatever).
I think this thread will help you along as well:
https://forum.customframeforum.com/t/converting-to-oxy-propane/533/31