do you have model number of those athenas?

it would be best to know the model of the athenas to know which center to go with

but i know the polk csi5 is good. i have the csi3, and i think it's good too. so if those athenas were only 350 for the pair, the csi3 may be a good choice. i've also heard good things about the Infiniti Beta C360.

and you should be able to get a decent pair of surrounds for a decent price.
fry's has sales on the RTi 4s for 150/pair. you might be able to find good deal on RTi 6s too. i've had experience with both and love them.