You could have found that information easily by searching for it.
But OK, I'll bite:
I have often recommended Rob Walling's "Start Small, Stay Small " as having a good introduction on landing pages as marketing tools. In addition to this book, there was recently a free edition of Hacker Monthly dedicated to the topic.
You can get a WordPress site up and running for less than $100 per year, including domain registration and hosting.
Design can be anywhere from installing a theme, which you could do yourself for free, to installing a paid theme (up to about $80), to designing a site from scratch. If you go that route, then it can cost anywhere up to tens of thousands of dollars, depending on what it is you're trying to achieve.
Running an AdWords campaign can be done on almost any kind of budget, depending on what words you're targeting, your price point, and how much you're willing to spend.