One has a catalog value of more than $1,000. On the back the owner wrote $1 for the value. The stamp was pen cancelled. Do pen cancels reduce a stamp value that much?
In some cases, yes. If it's a fiscal use of a high-value British Empire stamp, for example, it certainly can. There are a lot of pound-value issues that are only valuable either mint or postally used; the vast majority were used as revenue stamps, and are common as such.
In the particular case of your stamp? Well, you didn't tell us what you have.