When it comes to World coin collecting, I NEVER look for specific coins. You can spend a whole lifetime looking for just what you want.
For World collecting I frequent coin shows and dealers, and look through their higher priced junk boxes, with a completely open mind. That way, you can find interesting pieces from ancient times to current.
I have a preference for coins 1800 to 1900 in the best condition for price, although I will happily collect ancients from China and India, medieval European hammered coinage, milled coins of the 17th and 18th centuries, as well as Roman and Greek.
ebay can also be a good place to look, but since I am a cherry picker, my success rate in
ebay is very low, because I am always looking for that excellent value for money item.
With my approach to collecting, lots of patience is needed, as well as the talent to spot a bargain. In my case, the 'talent' is hard earned over a period of nearly four decades of experience.
My collection of World coins numbers about 2,500 and I would have about 200 coins over 1,000 years old. There are also a few gold coins in this. Most of the higher valued coins in the collection have been acquired as lucky low bids at public auction. Nevertheless, most items would be valued at less than $10 apiece.
My collection basically is a historical statement of the development World coinage since it's invention.