“ ‘We don’t know exactly what ‘rat poison squared’ is supposed to mean. What we do know is that Bitcoin created a very productive ecosystem and spawned the entire cryptocurrency revolution, which is driving innovation in nearly every industry.’ ”

That’s how ECoinmerce COO and crypto believer Rex Chen responded to Warren Buffett’s slam of bitcoin BTCUSD, +0.51% as “rat poison squared” at the Berkshire Hathaway BRK.A, -1.79% annual meeting earlier this month.

To mark the occasion, ECoinmerce is selling everything from t-shirts to coffee mugs bearing the “Rat Poison Squared” logo. Prices range from $19.99 to $39.99.