I have for sale an older set of 5.0 speakers from my home theater, since I upgraded. They are two different series in the Polk line, but sound very well together.

First up, the Polk Audio CSi-A4 5.25" Center speaker.
This was purchased floor model, so it does have signs of wear, I've shown some of them in the pics. Works just fine though, no issues with buzzing or rattling. Asking $25.
Name: 20190514_123228_HDR.jpg Views: 117 Size: 53.2 KB
Name: 20190514_123242.jpg Views: 116 Size: 60.8 KB
Name: 20190514_123246.jpg Views: 117 Size: 46.8 KB

Second up, a set, purchased new, still look new, of RTi-A4 5.25" bookshelf speakers. What's more to say, they look and sound great. $50 FIRM.
Name: 20190514_123517.jpg Views: 115 Size: 32.6 KB

And lastly, the mismatch of the bunch. Still mix well in sound with the others, but look different. A set of RTi-4. $35 FIRM. Again, can't say much more than they look and sound great, and work well in a surround setup with the others.
Name: 20190514_123648_HDR.jpg Views: 118 Size: 63.8 KB

So far, I've given prices if sold individually. If sold as a set, looking for $90 FIRM.