Best Buy via eBay offers the Polk Audio 6.5" 2-Way In-Ceiling Speaker for $59.99 with free shipping. That's $40 off list and the lowest price we could find. It features a 6.5" polypropylene cone woofer and 0.75" silk-dome tweeter.

Note: Best Buy also sells it as an open-box item for $52.99 with free shipping.