I have to finish up building my O/P setup. I picked up my oxygen concentrator about two months ago for $200 and a tank of Propane I can find at any gas station or even at Walgreen for about $40 a tank without a trade in and with a trade in it's like $15. Why wouldn't you not want to run a O/P setup? When Trek was still brazing their own frames they were using O/P. So it's not just some penny pinching backyard builders running this setup.