who makes the quietest air compressors?

How about a clue as to what you need? CFM? Tanks size? 220 Volt? For a nice quiet compressor you have to look at double or triple your budget. For $300 you will get a small Campbell Hausfeld. For $1500 you can look at Ingersol Rand

I'd check out some of the firms in SanFrancisco. The guys there really know how to blow, and are pretty quiet about it. However, they generally dont use oil, they use vaseline. I'd forget the vertical and go with the horizontal method, it's easier on your back. I think you could get one at least twice for $300.