One thing when buying older world Proof coins: watch out for the Franklin Mint.
In the 1970's, they flooded the market with coins from every corner of the globe... but mainly from tiny British dependencies (places like Cayman Islands, Belize, Barbados, Jamaica, etc.). The coins themselves are good enough, if proof coins are your thing, but the packaging was atrocious. Unless the coins were shipped off straightaway to the Moon, Tibet or some similarly airless, waterless place, the coins are likely to have not survived in pristine condition.
Their marketing tactics almost singlehandedly caused the crash in popularity of world coins in the early 1980's. The "Franklin Mint" still exists, but they don't make coins anymore. Funny, that.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis