For heavier items, Priority mail is not always cheaper, especially if you have to insure the item. Usually when a package is over 2 lbs, it's cheaper to go UPS or Fedex. Believe, me I've been therePriority mail is great! And it's usually cheaper too.
UPS owns the US Postal Service?priority mail is great and oh ya ups owns usps...my dad works for ups so you will be fine....