Some shoppers are bulk buying conventional 100 watt light bulbs before they are phased out, some independent retailers have claimed.
Many traditional bulbs will not be available under European law from 1 September to be replaced by energy-saving bulbs.
And some stores say many of their older customers are buying up to 50 old-style bulbs at a time.
But some of the bigger chain stores say the demand for the new bulbs was high.
One electrical shop manager from Cardiff said the old-style bulbs were flying off the shelves.
Lesley Urrutia, who has run Pilton Electrical in Cardiff for 25 years, said she normally sold around 10 light bulbs a day but was currently selling more than 80 a day.
She said: "Elderly customers seem to be the most worried because they don't like the new energy saving light bulbs.
"They are panic buying because they have heard they won't be able to get traditional light bulbs any more. I've checked with my supplier and that isn't the case.
"They will stop manufacturing them but will continue to supply me from their huge stockpile of light bulbs. They will run out eventually but customers are trying to get their hands on as many as possible now."
Many supermarkets and chain stores have already phased the old bulbs out before the new legislation comes in.
But corner shops and specialist electrical stores are continuing to sell the old-style bulbs until stocks run out.
It is hoped the new bulbs will lower household energy bills and reduce carbon dioxide levels.
Bronwen Jones, 67, of Merthyr Tydfil, said she did not like the new bulbs because they "gave off a different light".
"I've bought a pack of 20 of the old proper ones - they should last me a few years yet," she said.
'Full of mercury'
All types of opaque "incandescent" bulbs will be phased out from Tuesday while clear 100 watt bulbs will also start disappearing.
Stores are allowed to sell off existing stocks after that but importing more of the old-style bulbs will be punishable by a fine or prosecution.
Nigel Farage MEP, leader of the UK Independence Party, said the idea of banning incandescent bulbs went back to a heads of European Union meeting a couple of years ago.
He said: "We're getting rid of good light bulbs that give us good light from which we can read to be replaced by these new ones which really aren't terribly good.
"They are full of mercury which will give us all sorts of problems when it comes to disposing of millions or billions of them at the end of their life."
But Donnachadh McCarthy, founder of National Carbon Footprint Day, said the new bulbs were as good as the old-style ones and would save people money.
"The reason why people say they're rubbish is, just like the incandescent bulbs come in different sizes, so do energy-saving bulbs," he said.
"People often think they come in one size and they put in the wrong size bulbs and they think it's not producing the same light but the problem is they've got the wrong bulbs."
Some stores said they had seen demand increasing for the new light bulbs, with customers happy to switch from incandescent bulbs.
A B&Q spokesperson said the chain had seen "a significant uplift in demand for energy efficient lighting in store, and from September we are doubling our range of low energy light bulbs to keep up with the growing demand".
A Tesco spokesperson said its customers had been moving towards energy saving light bulbs, helped by promotions in its stores.