https://www.1ct1c.com/product/no-4-generation-vehicle-mounted-12v-300bar-compressor/ I bought mine here for $350, including shipping. It works great but is a little slower than the Yong Heng.
I was skeptical at first because it all seemed a little too good to be true, and the people who build these only speak Chineese. I first ordered the Yong Heng compressor off Ebay, and then I saw this a few months ago on YouTube. For all I know I am the only American with one, as I have seen nobody else on YouTube using these. Through research I was able to find out the guys who make these compressors are actually engineers that work for an Ameriican firm in Shanghi, by the name of JTC engineering. They actually make air cylinders, industrial compressors, and interestingly, components for internal combustion enginees for companies like Ford.
Now I am a Rescue Diver in one of my part-time gigs, and I used to be a fill operator at a Dive Shop, started when I was 12 years old for my uncle. I have been around SCUBA compressors all my life and like to think I know my way around them. So I had no idea how they were able to both make a compressor so small (the ones we use at the shop are the size of a Volkswagon Beetle, and they EAT oil), and one that didn't need to be water cooled OR oil. So I started doing some more research and found that what they did was basically take the cooling system for a car engine, surrounded the piston cylinder with cooling heads in 360 degrees, which means no water cooling. Needless to say I am impressed.
The low cost of these compressors has made shooting MUCH cheaper for me, and much more convenient. I am literally never out of air, and since I can fill my own tanks, I bought 4 used carbon fiber tanks off Ebay for $300 bucks from a fire station that had to get rid because the tanks were past the imaginary 15 year lifespan. I'm not worried about that as I used to inspect and repair SCUBA and SCBA tanks, and I have never had one fail hydrotesting in 40 years. Not to mention that the carbon fiber tanks are overengineered to a much higher standard than my aluminum SCUBA tank (which is good forever), there is no reason the tanks should expire other than the fact that DOT regulations specify it, and the bueacratic budgets require it. I saw people paying $777 dollars for a 9L tank and fill hose, or $500 for a 6.7 L and had I not had the experience and training I did, I would have spent about $2000 more for everything I have now.
If I can answer any questions or help anyone build a cascade system, etc., please let me know as I want you all to enjoy this as much as I do, and I want you to spend your money on shooting, not filling your tanks with free air.