The cost of a 30 x 40 pole barn ranges from $8,000.00 to $12,000.00 depending on what type of pole barn you want to build.
You can sometimes build a pole barn yourself cheaper than having someone build it for you but a good pole barn builder can erect a pole barn within a few days and usually less than a week.
My neighbor paid $12,000.00 for a 30 x 40 pole barn and was gonna build it himself but instead he had a builder build the pole barn and they had it erected within 4 days.
He could've built it for $2,000.00 less but it was well worth it to him to have the pole barn built by a quality builder as he didn't have to do any of the work as they did it all and it was done nicely and fast.