Governments tend to frown on the personal acquisition of radioactive isotopes. Well, there's a tiny bit in your smoke detector, but if you managed to get the eleven pounds that are in the MSL's RTG you'd make the international news.
Pu-238 isn't naturally occurring, and nobody makes it anymore. The US bought the plutonium that went into the MSL from the Russians, who are starting to run out themselves.
The other problem with RTGs is they get less efficient as they get larger. The one in the MSL only produces 125 watts, which will decay to about 100 watts at the end of its 14 year lifetime. That's not a lot of power.
Pu-238 isn't naturally occurring, and nobody makes it anymore. The US bought the plutonium that went into the MSL from the Russians, who are starting to run out themselves.
The other problem with RTGs is they get less efficient as they get larger. The one in the MSL only produces 125 watts, which will decay to about 100 watts at the end of its 14 year lifetime. That's not a lot of power.