You betcha Danny. Sometimes it's hard to justify spending "this" much or "that" on a particular part but in my opinion it is a necessity. I now have at least one extra of every type of spring for my Ak, including an extra extractor like you mentioned.
Springs are always first on my list. Some springs could easily be replaced by hardware store springs and/or springs of the same or similar dimension & tension. But where would you find an AK hammer or recoil spring if parts weren't available? Probably nowhere, and a part like that is necessary.