Update: I bought the GBC Proclick Punch and Spine. They meet my need perfectly!
Note: For those living in regions that A4 size is the standard, the Kokuyo binder and punch would be the perfect solution. However, two things prevented me from going with Kokuyo: 1) I want to use the 30-hole punched paper for smoother page turning, and 2) I want to use Letter size paper because that's the most commonly printed size in the US. GBC ProClick is designed for Letter size paper. The only drawback is their punch is quite expensive. Luckily, I was able to find one on eBay for less than half price.
Another of my specific requirement is the system to have spine that's very slim, as my current need for each book would contain no more than 20 pages.
Well, here is some picture to show how it works. First, the punch ($50) and spines ($15):

Punch can go through to 6 pages at a time. It's a pretty simple mechanical device, and very well made, so I don't see any problem buying used.

The spines packet comes with this little tool to open the closed spine like a zipper. If I ever lose this tool, a screwdriver would probably work, too.

After inserting the new pages, you close the spine by pressing on each ring so that little nub on one end insert to the other end with a slight click.

I added thicker card stock paper as front and back cover. The finished book stays on the music desk flat and page turns easily and smoothly.
