Lifeline Canberra Bookfair opens at 9am on Friday at Exhibition Park in Canberra.
More than half a million items - or eight semi-trailer loads - will be on sale.
The event continues Saturday and Sunday, with Saturday family day with fun activities for the kids.
One of the star attractions this year is a big collection of Paddington Bear books.
Lifeline Canberra CEO Carrie Leeson said there was also a treasure trove of textbooks among the bargains.
"This year we have moved our February bookfair to before the university school year so that students can pick up their textbooks from us, saving their valuable student funds but also giving to our very worthwhile cause," she said.
The book fair is the major fundraiser for the telephone counselling service.
Ms Leeson said each potentially life-changing call to Lifeline's 13 11 14 crisis support line cost the organisation $26.
"Sadly, on average one Canberran dies from suicide every week. We know that now, more than ever, we need to grow our crisis support centre capacity to answer every call and change lives for the better.
"...We want to ensure we have the funds to answer every call from those in need. Every handful of books purchased funds a call – that's a powerful purchase," she said.
Ms Leeson also thanked all the volunteers who make the book fairs a reality.
ACT Minister for Mental Health Shane Rattenbury encouraged Canberrans to head along to the book fair.
"Many Canberrans will need the kind of support that Lifeline provides at some stage in their lives," he said. "In lending an ear to people who are going through challenging times, Lifeline's trained crisis support workers can make all the difference."
One hundred per cent of the funds raised through book sales at the Book fair goes to Lifeline Canberra's crisis support centre.
As well as books for sale, there will be DVDs, CDs, vinyl records, puzzles, board games, sheet music, comics, maps, magazines and more for prices as low as 50 cents.
Book fair visitors are also encouraged to bring non-perishable food to donate to local organisation, Communities@Work.
Book donations are also welcome at the book fair, in addition to Lifeline's Mitchell warehouse.
* The Lifeline Bookfair is at Exhibition Park from 9am to 6pm on Friday, 9am to 5pm on Saturday, and 10am to 4pm on Sunday. Entry is by gold coin donation. Children's activities on the Saturday are from 8.30am to 1pm.