I do not think this set up is at all bad.
Better than most.
I'd lose the bubble counter, those things have poor seals and the hose connectors tend to be poor over time etc. A good barbed end is ideal.
If you wanted to make the best unit within reason:
Victor light duty reg(light means low flow volume, not wimpy)
Nupro Swagelok meter valve or the aquacave are decent:
http://www.aquacave.com/detail.aspx?ID=780
Perhaps AB or Rex etc might end up carry those, they are much better IME than the Clippards, which I have a lot of time with.
The solenoid can be like the one that's on there or a Clippard
The Tygon 1/8" tubing.
Or you could buy the AB one, it's still much better than most of the ones out there in the price range an folks do not have to monkey putting it together.
Like Chevy, make a cheapo, a mid level and caddy.
One for each budget.
The AC valve is nice due to the barbed end fitting very well to the Tygon tubing, and the 1/8" threaded end instead of that little 10-32 threaded tiny clippard that can get knocked and loosen thus causing a leak or if you want to use multiple manifolds and have issues with leaks etc, that little 10-32 thread + that little dinky rubber gasket is a poor seal for 10-20psi, okay for 1-2psi etc, but that's not what a needel valve is for in our case.
So a nicer thicker 1/2" threaded end is much better, that+ teflon ain't going anywhere. Add the Tygon, that's nice a flexible, there are not going to be much in the way of leaks etc.
Cost more? Yes.
However, I think spending more on CO2 is wise for regulation of flows.
The reg here looks decent to me.
But I have not used it either.
Regards,
Tom Barr