This is the current offer from LonelyPlanet.com.
If you spend £20 on their online site, you can choose a free encounter guide, worth £6.99! You have to spend £25 for free delivery, which should be doable.
The encounter guides have 40 books to choose from, with loads of bit cities like Paris, Dublin, Edinburgh, Hong Kong, Beunos Aires, and more.
Note: Don't forget to price compare your purchases before you buy. For example, buying the books on Amazon or something might be cheaper, so make sure you compare your deal and get the best offer.
HOW TO CLAIM:
Step 1: To redeem your FREE Encounter City Guide you need to spend a minimum of AU$40 / UK£20 / US$30 / EU35 in the online shop. This total excludes the Encounter Guide and delivery charges. Discounted orders must also reach the above totals to qualify.
Step 2: Once you have reached the minimum, head to our Encounter Guide page, choose the title you want and add it to your cart - it will list as FREE. If it doesn't list as free, please go back and check that you have met the minimum order requirements.