My father is a Locksmith and Safe technician. He moves safes all the time and I have helped him on numerous jobs. For a average gun safe (500-800lbs) it is possible for the owner to move it with some big friends and a furniture dolly. This usually ends up with scratched walls and maybe other damage. He does get calls to move these types of safes all the time, but when he quotes a price, the caller only calls back half the time. They feel that they can call a buddy and get it moved for a 6 pack of beer.
For anything more than 800 pounds, hire a pro. My father has special lifts, tools, skills, and 15 years of safe moving experience that makes things easier, but it is hardly ever easy. Most people don't understand that things like doorways, small steps, tight spaces, and other overlooked obstacles can be big problems if you don't know what you are doing. A 3000lbs safe is a lot of weight, and if that thing starts moving a way you don't want it to, good luck stopping it. We have seen safes that have fallen through floors and gone through walls. Thats bad time to realize you should have hired someone.
So bottom line, hire someone. A good safe technician/safe mover should be licensed and insured so if they do any damage, its covered. Would it be worth it if you dropped the safe through a wall or floor and then had to hire someone to get it out and then hire someone else to fix the damages?