collective.behavior.price provides price related behavior to dexterity content types.
The behavior can be added through the web or directly through the file system to the dexterity content type xml file like:
<property name="behaviors">
...
<element value="collective.behavior.price.interfaces.IPrice" />
...
</property>
You may also set currency through content registry and content price with currency will be also cataloged with metadata called money.