Walmart offers Onn. Compact Wireless Keyboard for Tablets and Smartphones for $6.88 (orig. $12.88).  Free shipping with Walmart+ or on orders over $35.

Product Description:

Type away with our onn. Compact Wireless Keyboard! We've got the key to a wireless typing solution for your tablet... our Compact Wireless Keyboard will keep your desk neat and tidy with no messy cables laying around. Connect to your tablet or mobile device easily through via Bluetooth Wireless Technology and enjoy your cordless workspace! Surf onn. with our onn. Compact Wireless Keyboard.
We're onn. to something here. We took the hassle out of buying electronics and built a brand that's fresh and simple. With delightful pops of color, finding the right product has never been easier. Say goodbye to stressful decision-making and fear of the electronics aisle. Our mission is simple... to deliver great products and make it easy. Choose onn. and get back to using your brainpower for the important things in life.. like pondering the question, "What should I binge watch this weekend?"
Includes: ONN Compact Wireless Keyboard for tablets and smartphones, charging cable, and welcome guide

• Broad Compatibility: Onn. Compact Wireless Keyboard is compatible with all four major tablet operating systems (iOS, Android, Mac OS and Windows).
• Unfold for Convenience: A simple unfolding of the stand from the bottom of the keyboard will allow you to place your devices at the perfect angle and be set up in seconds. 
• Long-Range: Bluetooth technology allows for an operating range of just over 7 meters. 
• Switch Easily with Multiple Bluetooth Channels: With the press of a button, switch between up to three devices with ease.
• Quiet Keys: Low-profile keys means you can do what you need to without loud keys clicking away. 
• Travel-Friendly: With a low profile and slim design, take compact wireless keyboard anywhere.
• Includes: ONN Compact Wireless Keyboard for tablets and smartphones, charging cable, and welcome guide