What surround speakers for polk r50 & CSI25?

[alfa147x]

What surround speakers for a home theater with the front left and right polk r50 & the center CSI25

Should i go with the Polk RM8 ? the tweeters seem to be the same
Also i dont want to spend more then $200 for a pair
oh and they need to be wall mountable

Thanks,
Alfa147x