help matching a center speaker to fronts. How to?


I bought 2 Wharfedale Valdus 500's (discontinued)for a 5.1 system. What i didn't realize is that i would need a matching center for 'em. Still can't find it. Does anybody know where i should look for it (center Wharf Valdus)?
Another option is to match soething else to it. I have no clue how to go about it. What brands can be matched with my 500's? How do i match them? Any help will be appreciated.

thanks ahead

I saw an add for a box;by Jolida that 'says'it can help with unmatched speakers--for 35 bucks.--??