Booksellers who hosted Harry Potter parties on Friday night said they had "very successful" events, with "strong" sales of the sixth book.
However, they also expressed concern about the long-term impact of supermarket multiples selling the book at less than half the recommended retail price of €25.99.
Booksellers had described as "outrageous" moves by Dunnes Stores to sell the book, Harry Potter and the Half Blood Prince, for €9.99, and by Tesco to sell it at €12.99. Eason is also selling the book for €12.99.
Derek Hughes, executive chairman of Hughes and Hughes, said he was delighted to report very strong sales of the book over the weekend.
He had been particularly vocal in his condemnation of the supermarkets, saying it was awful to see "non-booksellers jumping on the bandwagon in a way that will have an enormous negative impact on the small booksellers, who struggle to make a profit 10 months of the year".
Yesterday he said sales in the Galway branch were significantly up on those of the last Harry Potter book in 2003.
"Shannon airport sales were marvellous, Dundalk sales were superb and St Stephen's Green was very good. All the shops had a really good buzz about them," he said.
There appeared to be an impact from the supermarkets on Saturday morning. Compared with 2003, when there were hundreds coming into the shops when they opened early after the midnight parties, he said things were slower this time.
"It will be in the coming weeks that we'll see if the supermarkets really affect sales badly," Mr Hughes said.
Niall Mescall, manager of Reads, also reported a slackening on Saturday morning compared with 2003. "It wasn't as good as last time. The supermarkets did knacker things a bit, but there was a huge queue on Friday night, over 300. There's great store loyalty. But on Saturday we sold 115 copies in the first hour of opening which is good, but it slowed to a trickle after that," he said.
Around the world Harry Potter and the Half Blood Prince is expected to be the fastest selling book of all time. British book chain WH Smith reported sales of 13 books per second across the 391 shops it opened early on Saturday. Author JK Rowling is said to be set to see her fortune grow by about €40 million as a result of the first-day sales alone.
