Here is what I have found through attempting to do something similar. I have a couple airbrushes (2 Badgers and 2 Paasche's), that I wanted to connect to my Badger compressor. I found a cylindrical manifold with three output holes that I screwed knife valves into to turn air flow off and on. I put the entire thing on the output side of my regulator coming off the compressor and tied it all up with Teflon tape. The whole thing ran me maybe $20 so it's easy to do it yourself.
Now the downside. I found that my compressor ran constantly (tough on a small airbrush compressor). I also began to have issues with my output pressure and my pressure switch. I do not know if these are related. So first, I would recommend a more heavy-duty tank-style compressor if you want to make a manifold, an airbrush compressor is likely to struggle.
I also found that Paasche and Badger airbrushes have different sized air input connections (you can't use a Badger hose on a Paasche and vice versa, they are different sizes). So while the QD idea is a great one, you will need to find some kind of universal female end that has the male ends available in various sizes if you use brushes from different manufacturers.
Ultimately I ended up scrapping the manifold and using QDs because my little compressor couldn't handle it. I have since obtained a porter heavy duty compressor that I will likely attach my manifold to as I think my Badger compressor is on its last legs.
My suggestion -
If you want to have a manifold system, it's easy to do yourself. Just make sure you watch your valve handles to make sure they are clear to swing freely (aren't hitting other parts). If you want to use multiple regulators, they are a piece of cake to simply screw into the output side of one of the manifold vents. You wouldn't need anything else to step down the pressure, just the regulator. I would recommend staying away from a circular-style manifold, it was more problems than it was worth. If I had to do it again, I'd do a T-style or several in a line. The big things are to plan it out, use Teflon tape at EVERY joint, and use a bigger compressor. Keep in mind the big ones are noisier.
Groot