I had to buy switches both N/O and N/C of the same type. I got them both as four-switch packs at Radio Smack. They called yours out as normally-closed in their catalog, but fail to label the normally-open as such.
Here you go:
Mini SPST 0.5-Amp Momentary Switch (4-Pack) - RadioShack.com
These are what you want, at RShack. They are the same cheap failure-prone junk as your first find. BTW, the red and black plungers don't indicate which type you are using, both packs have two red and two black. Use labels!
Take care,
kenjj