TORONTO -- Booksellers are having a tough time predicting which Canadian author will win tonight's prestigious $50,000 Scotiabank Giller Prize for fiction.

"I think Lisa Moore is going to win, but I think you could throw the books down the stairs and whichever went furthest would be the winner," says Ben McNally, owner of Ben McNally Books in Toronto.

"I don't know that anybody's got a really firm prediction on this one," says Caroline Walker, inventory manager at McNally Robinson Booksellers in Saskatoon. "I think it kind of could go a lot of different ways."

McNally says at his store, "Caught" (House of Anansi Press) by St. John's-based Moore -- which is also on the short list for this year's Rogers Writers' Trust Fiction Prize -- has been outselling the other four finalists for the Giller, which is into its 20th year.

It's also been outselling its Giller competitors at Walker's store, but that could be due to inventory issues.

Walker says the hardcover of German-born finalist Dan Vyleta's "The Crooked Maid" went out of stock at their store "a while ago."

She says they ordered it from publisher HarperCollins Canada as soon as the Giller short list came out Oct. 8 and it only arrived at the end of the month in paperback edition.

Walker says HarperCollins also "couldn't supply" the store with "a big order" of hardcovers of Toronto-based Dennis Bock's shortlisted "Going Home Again," but the store did receive the paperback edition at the end of last month.

And Edmonton-based Lynn Coady's nominated short story collection "Hellgoing," published by House of Anansi, "also took quite a while to come back into stock," adds Walker.

This year's Giller finalists also include Toronto's Craig Davidson for "Cataract City" (Doubleday Canada).

At Book City in Toronto's downtown Annex neighbourhood, manager John Snyder says no finalist "is really outselling the others. There's been a lot of interest in all of them, as usual."

Indigo Books & Music Inc., says "there isn't a frontrunner as far as the sales go" at their stores, which also had "inventory issues" with the two HarperCollins titles.

"Those two were the ones that we couldn't get inventory of either, so we sold out very fast of those two books," says Bahram Olfati, the company's vice-president of procurement for books.

"But the other three have been selling amazingly well."

So well, in fact, it's been one of the bestselling years Indigo has had for the Giller short list, he says.

"This year in particular, the short list has outsold any other year in recent memory. It could be to do with how well-known the judges are," says Olfati, referring to CanLit legend Margaret Atwood, 2011 Giller winner Esi Edugyan and American author Jonathan Lethem.

"I think it's actually a combination of how well-known the judges are, how good the books are and the growth of the Giller Prize itself."

It's a different situation at Walker's store, though, where sales of the Giller nominees have "been a little slow" compared to last year.

She thinks that could be due to the short supply as well as "the lack of sort of more recognizable names" on this year's short list.

One big name that didn't make the cut, to the surprise of many, was former Giller winner Joseph Boyden for his bestseller "The Orenda."

Both Walker and McNally say that title, which is a finalist for a $25,000 Governor General's Literary Award, has been outselling all of this year's Giller-nominated titles.

The Giller Prize was created by businessman Jack Rabinovitch in memory of his wife, literary journalist Doris Giller.

The winner will be unveiled tonight at a black-tie Toronto gala broadcast live on CBC-TV.

Last year, Calgary's Will Ferguson nabbed the prize for "419."