Center and surrounds for B&W 802d

Hi this is my first post on here so please bare with me if this isn't the right place to ask. 

I recently purchased a pair of B&W 802d's and now I'm starting to get the audiophile itch as I start seeing and researching the possibilities.  What would be some recommendations that I should consider for a center channel and surrounds?  Prices are all over the map for used speakers and I'm not totally sold on just outright purchasing brand new. 

Thanks!