Forgot to add this one to my list-
Dealers who make a deal with a mint to offer up exclusive sets.
APMEX is one of these dealers, seeing they do the Libertad sets, the more recent
Perth Mint Kookaburra set and a few others.
My advice to everyone is to wait until other dealers come up with the single coins, sometimes already graded and at auction.
No need to pay for the dealers mark up just because it was an "exclusive" of theirs.
If you wait patiently, these type sets usually end up coming for auction after a some months pass by.