We are looking to set up automated UI tests and were wondering what the best approach is, what are the potential pitfalls, is it expensive to set up?
We've been doing Automated UI testing successfully using our own home-grown tools and libraries based on the Microsoft UI Automation framework. It has been a bit of steep learning curve, but worth it.
I recommend reading up on the Michael's Automation Stack to learn how you might structure your code. You might also find my Introduction to UI Automation useful.