Books sales are dependant on what buyers are looking for and how much they are prepared (or can afford) to pay. Sellers are competing with the libraries, charity shops, free cycle, book stores, discounted high street stores, supermarkets and all the other online sources that can afford to offer free postage on larger orders. For new books, I'd price check online and then order from wherever is cheapest, so beating those prices (including P&P) is paramount IMHO. In saying that, I need to admit to living in Scotland's national book town, so my options are somewhat greater than elsewhere, but I STILL have problems getting what I want, when I want it at a price I am prepared to pay. Most new books I buy are for gifts as they have become a luxury many can't afford.
Now's the time to start promoting all the festive bargains