You forget that they need to make profit. They need at least a markup of 30%. Most likely more, since they buy several copies at once, and can't excpet to sell them soon.
On top of that, they have to pay VAT (5% - 20%), and need to charge you that amount, too. VAT for the full price, which includes book price, shipping, and their markup.
So don't expect to pay less than 150% of the books price.