Amazon offers Prime members the Britax EZ-Cling Sun Shades 2-Pack, model no. S865000, for $6.79 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping adds $5.22) That's $3.40 per shade and the lowest total price we could find by $3. These 19x12" shades feature UPF 30 plus sun protection.
Amazon offers the Britax Parkway SG Booster Seat in Onyx, model no. E9LA869, for $72.99 with free shipping. That's $11 under our January mention and the lowest total price we've seen for this booster chair. (It's a current price low by $27.) It fits children from 40 lbs. to 120 lbs. and 38" to 63" and features side impact protection, seat belt guides, and a removable cover.