Yes, the Book Market does have a good selection of books, but all of them - good condition or not - are overpriced. You could buy the same book from Chapers or Amazon for less - and that's including the shipping!
They're buy-back of used books is a face. 10% back on 'their' bought books, and only 25 cents back for each used book that you bring in for trade. Those same books are then put onto the shelf at a price that exceeds those of retail stores.
Personally, I'm sticking to Chapters and Indigo. Their customer service mandates are better, and they keep cleaner stores.