How much does it cost to ship a package at the post office? Compare Mail Services Service Starting Price Priority Mail® $7.70 (at Post Office & Online) $7.16 (Commercial)6 First-Class Mail® $0.58 (at Post Office & Online) $0.426 (Commercial)6 First-Class Package Service® $4.00 (at Post Office) $3.01 (Commercial6) USPS Retail Ground® $7.70 (at Post Office) […]