A good way to go, ( and cheap!) is to get a tank from an 18 wheeler. You can even get them with mounting brackets. They come in all shapes and sizes. Peterbuilt and Kenworths sometimes have aluminum tanks which are nice. I managed a truck wrecking yard in Fresno, and we sold tanks for $75 with the brackets. They usually have at least 4 bungs with standard pipe threads.
You can get the synflex hose that they use for trucks pretty cheap, and the fittings are easy to assemble.
I have a York 210 A/C compressor. You can get a used one at a wrecking yard for under $75. I got the everything to maintain the tank pressure, (pressure switch that turns the clutch on and off, unloading the compressor output line when it turns the a/c clutch off) at Grainger. ( I love that place)
I think the ARB will operate with 85 to 120 PSI. So you have a range to work with. I know they take very little air to operate. I have a friend up in Washington that has a small tank that can't be bigger than a quart to run his ARB off of.
I hope that helps!
