Toilets
The simple thought that there might be a market for illegal toilets is evidence of how strongly people desire contraband. What kind of toilet could possibly be prohibited? It's actually easier than you may imagine.
The Energy Policy and Conservation Act was enacted by the US Congress in 1994. The water that goes through toilets is controlled by that law. The maximum amount of water used per flush was 1.6 gallons, which was less than half of what typical toilets consume. Although it was an attempt to conserve water, not everyone endorsed it. Some folks desire toilets that flush with the sound of a shotgun being fired. Others complained that the so-called "energy saving" advantages of the new toilets were pointless because they needed to flush several times. The environment isn't really being saved if you flush three times, is it?
In the US, it was therefore unlawful to sell old-style toilets, but it was not unlawful to own one. Therefore, Americans might drive to Canada, where the toilets were still available, and make purchases there before bringing them back to the United States.