Walmart has the Blaupunkt 6.5" 360W 4-Way Coaxial Speakers for $9.99 + $5.99 shipping fee = $15.98 shipped. List price: $15. Feature mylar dome tweeters and a 80Hz to 20kHz frequency response.
Amazon has the AmazonBasics BSK30 Wireless Bluetooth Speaker (red or black) for $12 with free shipping for Prime members or on $25+. Has good Amazon Reviews.
Walmart has the Pioneer Bluetooth Receiver & Speaker Bundle with a Pandora Premium 3-Month Trial for $70 with free shipping. List price: $160. Features include Pioneer Smart Sync technology and four 6.5" coaxial speakers.
eBay has the Vizio SmartCast Crave Pro Bluetooth Speaker (SP70-D5) for $90 - 10% off with coupon JUST4YOU (Ends 3/20) = $81 with free shipping. List price: $250. It features a two 2" full-range drivers and two 5.25" subwoofers, 40Hz to 20kHz frequency response, 802.11n wireless, built-in Google Cast, USB, and Bluetooth 4.1, remote access via the Vizio SmartCast mobile app.
Amazon has the ELAC Debut 2.0 B5.2 Bookshelf Speakers, 2018 model (DB52-BK) for $190 with free shipping. Has excellent Amazon Reviews.