Bimetallic coins have become increasingly popular with the world's issuing entities since their inception over a decade ago. I believe it was the French who first produced these lovely innovations in 1988, and now several dozen countries have issued several hundred types. There are more than a few world coin dealers who have a subspecialty in bimetals, and a few who are attempting to trade in nothing else.
Though the normal scheme of bimetal issue is to reserve them for the high denominations, most of them are still cheap enough to be affordable to the low budget collector - a few dollars each on average. And, with a few exceptions, most of them were made in large quantities for circulation, so they are reasonably easy to obtain.
The big worry when these coins were introduced was that they'd fall apart in use, but that hasn't happened. Hundreds of millions of them are in circulation around the world, and that problem just has not occurred. There are very few mint errors of missing rings or missing centers, few enough that those which do show up (as was the case in the first year of the Canadian polar bear two-dollar coins) the story made the front page in World Coin News. I'm a dedicated browser of WCN, and I can't remember seeing mention of other bimetal errors since then. It would appear therefore, that the error rate of bimetals worldwide is lower than that for the more conventional coinage of the United States as a whole. Could this possibly be so?
Along with the ever increasing number of circulation issues are a few struck in precious metals for the edification and amusement of collectors. As with the circulation strikes, the French led the way with these confections, striking a collector version of the regular 1988 10 francs coin with a gold ring and a center of silver-palladium alloy. Other types followed. The basic market situation with these is that you can look around for them all year long and not find a single one. They are rare and expensive, but probably the potential buyers are even more rare. Certainly no one has ever asked me about them.
In terms of expressed collector interest the prom queen of the bimetals is probably the Mexican 50 pesos. A crown-sized coin with a silver center and a catalog value of $25.00, these have possibly been the most frequently demanded coins in my experience over the last few years. They are hard to get and easy to sell.
Given the outstanding success of these coins throughout the world, one has to wonder about the prospect of American bimetals at some point. It is a well-known fact that our mint officials are extremely conservative, and that a decade of experience would mean next to nothing to them. Look how long it took them to change the paper money! It seems reasonable to hope, however, that after sufficient observation and study, say thirty to fifty years, that a cautious essay might be attempted - a "quarter eagle" perhaps. I'll plan to check back on this subject around 2025.