Now recreational users have an expanded menu of drugs to choose from, at much lower, recession-friendly prices.
"It's a lot easier now," said Thomas, 19, a slightly scruffy college student who declined to give his last name. "It's all legal at the moment."
He had just bought a packet of Ice Gold, an "aromatherapy resin extract" by a company engaged in "botanical research." Two grams cost about $35. Thomas buys a packet a week to take home and smoke; he no longer has to badger friends for pot. (Online discussions say Ice Gold contains resin from cannabis, but shop workers insist that it "has no cannabinoids.")
Nothing on the box, though, says exactly what's in Ice Gold or how to use it safely. There's only an effusive, but not particularly helpful, description of how such plant extracts "have for millennia been used in shamanic rituals."
That lack of information upsets Christopher Luke, a vocal critic of head shops in the southern city of Cork, where a store called the Funky Skunk sits on one of the main shopping drags.
An emergency room doctor, Luke has seen some of the ugly outcomes of unregulated drug use.
"The consequences of head shop products are sometimes spectacular in terms of psychosis, delirium and what they need in terms of treatment," he said.
His hospital admits a head shop case every week to 10 days, adding to the strain on Ireland's overburdened healthcare system, Luke said.
"Head shop drugs are in every village and town of this island," he said. "Even if 1% of consumers come to harm, it could be very, very difficult."
Like others, Luke counsels against rushing through inadequate or ill-thought-out legislation to deal with the situation.
But Costello, the lawmaker, said some stopgap measure needs to be taken now, especially if Ireland wants to avoid turning into a destination for the legally blissed-out.
"We leave that type of tourism," he said, "to Amsterdam."