You might look into the Irish gunmoney, token coinage issued by James II during his unsuccessful attempt to reclaim the British crown in 1689-90. These bronze coins, supposedly made from the metal of cannons and bells, were mostly half-crowns, issued by month to the troops, with the promise of redemption for silver coinage at the end of the campaign, a promise that was never kept. These coins used to be plentiful, but now, as with many other coins, prices have increased. Still, you might have some luck finding a nice example during your trip. Here's an example, a half-crown dated "Jnue" (June) 1690. It seems that the engraver might have had a wee bit too much whiskey when working on the date!