They have exotic names like Funk Pills, Amsterdam Gold, Kratom Leaf and Ayahuasca Sacrament and promise effects which range from the mildly euphoric to "ecstasy-style" energy rushes and hallucinogenic experiences.
But these are not drugs where you have to break the law to sell, buy or consume them - they are all completely legal. Dozens of new and ancient types of "legal highs" - derived from herbs, plants and cacti from South America and Asia and synthetic stimulants from New Zealand - are available. They can be bought, often at low prices, from internet-based companies and an increasing number of high-street "head" shops.
Ironically, the trade has been stimulated by the Government's decision last year to ban "magic mushrooms", which contain the hallucinogenic psilocin, which had been sold openly through the internet and in places such as Camden market in north London. The ban left a gap in the market, with consumers and vendors looking for new products.
Mark Evans, of everyonedoesit.com, one of the leading internet-based mail order operations, said the increase in trade since last year had been "massive". He added: "There is a huge gap in the market. These consumers are not going to disappear, they are just looking for alternatives." Mr Evans, whose company also sells cannabis seeds for growing, said there had been a change in the culture of people who consumed recreational drugs. "We do a lot of festivals and speak to people who say they are fed up with dealers and taking drugs - like ecstasy - where they cannot always be confident that they know what is in the pill. People want something which will not poison them and they [want to] know what they are buying."
Although many of the organic-based legal highs have, it is claimed, been used in primitive communities for millennia, the current biggest seller, Funk Pills, have only been in existence for a few years. Sales have rocketed in the past six months. Selling for between £5 and £7, they come from New Zealand, where they are made by companies licensed by the government there, after it decided that they were a less-harmful substitute for illegal drugs such as methamphetamine.
Also known as pep pills, they contain the stimulant benzylpiperazine - banned in the US, Denmark and Australia - with other chemicals from the piperazine family, which are also used to create Viagra.
According to DrugScope, the independent advice body, while some users are keen on the pills, attributing genuine ecstasy-style effects, others are more sceptical. The pills come with warnings about dosage, driving or using machinery, and side effects can include those normally associated with ecstasy or amphetamines, such as dehydration, anxiety and insomnia.
Another big seller is the Spice Smoking Blend, a new version of the herbal mixes which are traditional legal alternatives to cannabis. "Herbal substitutes were always a bit of a joke, but many people say these are the closest thing to marijuana yet," said Mr Evans.
At the other end of the scale from Funk Pills are the £12 peyote cacti sold by Chris Bovey, who runs another mail-order company, Potseeds.co.uk, based in Totnes in Devon. Peyote cacti contain the hallucinogenic drug mescaline, which has a similar effect to LSD and was the drug used by Aldous Huxley before he wrote The Doors of Perception, which encouraged the use of mind-altering drugs in the 1960s. Native American tribes have used it for centuries as a shamanic plant that can create visions of an alternative world. "It is a lot more in demand since the mushroom ban," he said.
Mr Bovey said consumers broadly divided into two groups - older "hippie" types, used to smoking cannabis and younger buyers seeking to replicate the "E" experience. Instances of addiction, abuse or harmful effects were almost non-existent. The Home Office said there was no reason to examine the legal status of any of the substances on the market.
Nevertheless, DrugScope issued advice to students in London earlier this year, cautioning that any drug which has a psychological effect can prove difficult to stop if used regularly. It added: "Proper controlled research is sparse, and therefore side effects and possible dangers when taken with other drugs and even foods is not known."
Harry Shapiro, a spokesman for DrugScope, added: "People with mental health problems should not take them. If you are going to experiment, do so in a safe and secure environment."
* PEP PILLS: Marketed as Funk Pills or Party Pills and made from a chemical derived from the pepper plant. Developed as a worming treatment for cattle. Replicates the rush of ecstasy, but users should be careful of overdosing. £5-£7 for 2-3 pills
* AMANITA MUSCARIA (FLY AGARIC): Red- capped, white-spotted mushroomlong known for its psychoactive effects. Not covered by the Government's ban on "magic mushrooms" since it does not contain psilocin. Users should start with low doses. £14 for 12g
* KRATOM LEAF (above): Leaves of the Mitragyna speciosa tree of Malaysia and Thailand. Described by PotSeeds as "one of the most effective and pleasurable psychoactive herbs". Said to cause a dreamy sensation. Can be addictive. £9 for 5g
* SALVIA DIVINORUM: Herb that can create an intense high lasting less than an hour. Not recommended as a recreational drug. £10-£17 a bag
* AYAHUASCA SACRAMENT: A shamanic plant potion, it can induce vomiting before narcotic effects begin. Should not be mixed with with antidepressant drugs. £4.99 for 30g