Which center channels will work with the TSI 100s?

I reached out to Polk with this question and they told me the center channel I need is the CS20. I am piecing this system together on a budget, and was considering the CS10 as an alternative, but also the older Monitor series CS1 or CS2. I have seen some folks suggest those will be a "good enough" timbre match. I have found some local sales on the CS1 for $40-$50, and was wondering if I should go for it? This setup is in a small room (10 x 14). Any advice or suggestions would be greatly appreciated. Thanks!