A quality lower bj will run $30-$40, uppers are more because they include the control arm. Shop prices for Moog brand Problem Solver ball joints. RockAuto, Amazon, eBay and Summit are good places to look. Explorer Forum members get a 5% discount at RockAuto (with discount code) but you'll pay for shipping. I buy parts where ever I get the best price + shipping. You have to be careful with RockAuto shipping charges, because if multiple parts ship from different warehouses, you pay extra on shipping.