Price does not equal safety. Being educated about car seat safety equals safety! So if you can't afford the Britax Frontier 85, don't fret! There are safe seats in every price range.
Some great combination seats are:
Britax Frontier 85 (you already knew that

- FFs to 85lbs, boosters to 120lbs, around $225)
Graco Nautilus (FFs to 65lbs, boosters to 100lbs, around $150)
Evenflo Maestro (FFs to 50lbs, boosters to 100lbs, around $80)
Safety 1st Apex 65 (FFs to 65lbs, boosters to 100lbs, around $100)
ETA: BRU does not carry the Maestro and Apex 65. If you wanted the Nauti from BRU, it would be 135 after the 25% off plus tax and gas to drive to the store. You can get it at Amazon for 139 with free shipping and no tax. The Frontier 85 would be 210 at BRU after 25% off plus tax and gas. It is 210 from Amazon with free shipping and no tax. BRU is almost never the best deal even with the 25% coupon.