checked ebay and they are a lot cheaper than at a regular store. mowcious which shield would you recommend??
It completely depends on whether you need the extra little things on the 'better' ones. The cheapest one would probably do most people fine.
I have not got any real experience with any of the ethernet shields as I have never owned one (but have used one), so I couldn't really recommend one. Just go with your gut! 
Mowcius