Taking the Mezuzot when one leaves a rented apartment

Q: Can one who put up Mezuzot in a rented apartment take them when he leaves?
A: The basic Halachah is that one may not take the Mezuzot when leaving when a Jew is moving in there. There are, however, some solutions:
1. It is certainly permissible to take the Mezuzah Case.
2. One may replacement the Mezuzot with the least expensive, kosher ones available (Ha-Rav Mordechai Eliyahu on Kitzur Shulchan Aruch 11 #20).
3. One may take a Mezuzah which he put up in a place where a Mezuzah is not a requirement but he wanted to be strict.
4. One can ask the new tenant to pay him for the Mezuzot, but he is not required to do so (see Rama, Yoreh Deah 291 and Be'er Golah ibid.).