HOSES: Buy only the best , Yellow Jacket or other American manufactured hose. Yes they are $45. to $75 each but there is a drifferance. Not the cheap Ebay hose and gauges manifolds. 1/4", 3/8", 1/2"
Keep extra on hand so as soon as you find a problem you fix it sonner then latter can cost you a customer or a compressor!. Don't buy the cheap service fitting either they some times leak, leak vacuum (air into the system!) and other problems.