I'm really annoyed that I will never ever be able to complete my collection.
The only ones I'm still missing are:
Rb, Cs, Lu, Rh, Os, Pt, Yb, Th, U
I soon will buy the Lu and Yb samples. They are affordable. I also have a source for Rb and Cs, although they are not really cheap. I just purchased 100 grams of CsBr, which makes for more than 60 grams of Cs, but I also plan to buy some elementary Cs and Rb in glass ampoules.
The metals Rh, Os and Pt I will buy as very thin foils with a good surface area. Of course it is better to buy bulk quantities, but especially Rh is insanely expensive and well beyond my financial resources.
Two elements which I will never obtain are U and Th. Where I live, there is an absolute and 100% tight regulation of ANY radioactive material. I can buy HNO3, KClO3, red P, I2 and many other chems without problems, but thorium and uranium (and all of their compounds) are absolutely forbidden. Recently, someone's house was raided, because he had a sample of depleted uranium (IIRC almost 30 grams) and the whole street was upset. People were horrified by the nuclear disaster, which could have happened to them
. How the police could know that guy had uranium, I don't know.