Ideas for a good but easy-to-use game engine for an XNA project


I have been looking around and the best engine I can find is this: The problem is a full licence starts around £18,000 which i just cant afford in the real world.

So ...

I'm looking to do something unique in my project that involves dynamic terrain that can be moved in realtime whilst the user is in game and "stood" on it, other than that it's pretty much the same as any other WOW clone out there.

I'm also looking for something that (if i decide later to consider this a serious career option) would be taken serious by the industry as a real skill set to have.

Any ideas?

-- EDIT -- I am already an experienced developer but I build line of business applications for pushing data around between companies and departments so I don't need guides / tutorials as such.

I have also done a bit of XNA myself (tried building my own engine) but decided to use a prebult engine to reduce my project lifecycle.

Vanquish is what we are currently working on, but QuickStartEngine has a lot features including terrain.