Update [1/17]: Sold out at Amaozn, but still at Target.

Amazon has the LuMee Halo Light-Up Selfie Case for iPhone 12 & 12 Pro (Holographic Design) on sale for $9.99 with free shipping on $25+ or with Prime. Rechargable battery provides up to 30 minutes of lighting at full brightness. Also at Target in black and gold.