Bulk hunting is a great way to get rare coins. Most coin dealers know nothing about foreign coins. Its best to learn all you can about a certain country and then hunt the bulk coins looking to get a good deal. French, German and British coins are always great if you know a lot about the countries and can spot rare die varieties since most dealers consider them little more than bullion or curiosities. Some things I always look for in bulk coins:
1) Victoria Bun Head pennies. Most dealers sell them for around $1 or so and for a common date, common variety Bun Penny it is worth about that much. BUT there are so many varieties and many are worth $$$ if you invest your time and energy to identifying them.
2) Smaller sized or lower-purity coins. For example, a 1946 British Sixpence is 50% silver, on the other hand a 1947 Sixpence is copper-nickel, a lot of dealers will get the dates for foreign coin turnovers wrong and may toss a 1946 Sixpence in with the copper-nickel coins. Similarly some coins like silver threepence are simply not worth it to market it for bullion so dealers may toss them in with the copper nickel simply to get rid of them rather than stick them in 2x2s and sell them for a few cents for silver.
3) Coins priced less than their face value. For example, I've seen Canadian quarters going for 15 cents in the junk bin. You can easily make a 10 cent profit simply by picking it up and spending it, even if you are in the US.
4) Tokens. Even if you aren't a token collector, you can often pick up tokens for less than "face value" at some coin shops, often for local businesses/car washes/arcades. Similarly, you can often find worn older tokens from the '30s or so.
The key is to be educated. No coin dealer is an expert on /everything/ most have one or two specialties. A coin dealer who knows every VAM variety by heart might not know a thing about tokens other than they are curiosities. Know silver dates for all countries possible, and their purities. Invest in some specialty publications of the coins you wish to specialize in, or read internet sites about them.
Also, one thing to make sure is to know the years/purities of Mexican coins. It is a /very/ weird country to try to cherry pick coins from. Unlike most countries, Mexico started and stopped silver coin production many times in its history. For example, the 10 peso coin was silver until 1974, but then in 1992-1995 it started having a sterling silver center and a brass ring, then it became all base metal again. The one peso coin perhaps is one of the most deceptive coins, because while earlier coins were 90% pure or so, the 1957-1967 coins are only 10% pure. These are huge coins, bigger than a half dollar but they only have about $1 of silver in them because of the low purity.
http://www.cointypes.info/mexico/index.htm
Is a good site to find out info about the confusing series of Mexican coinage.
think i did okay for 10 cents
