The way things change in this field, I'd try to get the (matching) center at the same time as you get the front R/L speakers. Once they discontinue a speaker line, finding a timbre matched center may post a challange.

dunno if they have 'em near you but Best Buy (yes, THAT Best Buy) has Athena Audition AS-F1's on sale for about $200/pair or half their original price. These are well served by the matching AC-C1 center speaker and would do a fine job in your system. Just a little something to think about.