Exactly!
Cost depends on the expected value or cost of the job. In my case I bartered for the Frame work, drywall, insulation but paid $4k for the electrical. When I applied for my permit I claimed the cost or value of the job concervatively at $15k as it was about the value in goods that I did the barter with. The permit cost me about $500 and they give you plenty of time to complete.
Where I think it's a good idea is when you go to sell you have proof that everything was done to code. I had a big problem with my last house when selling it because when I bought it it only had electric baseboard heat and a wood stove. I had natural gas installed to the house and then bought a natural gas faux wood stove from the local dealer in Conifer who had a list of licensed installers to have it installed. After choosing one and having it installed I never knew or thought to get a permit from the county yo have the work done and the installer also never said anything about it either. When I went to sell the house the people interested in buying once we were under contract asked about any work that I had done to the house and if I had permits for the work. The gas stove that I had installed didn't have a permit fir the work done so I was required to have the stove and the work inspected and then had to pay to get it approved anyway. So I ended up paying a lot more in the end by not having a permit to have the work done in the first place!
A permit is also a huge plus for me this time because each step is being inspected by someone qualified to make sure my hired contractors are doing the job right, not cutting corners and using quality materials. Have a series of five inspections to get passed the first was electrical rough in, the second is framing inspection (free floating walls were required on anything not load bearing which I thought was overkill for being on top a granite mountain and not prone to frost heave), then there's an insulation inspection, drywall inspection, texture and paint are required before final electrical, and then a final inspection.
This basement finish is half the size of my house and a big job. Been at it for a month and a half already. The hardest part is getting contractors to show up when they are suppose to lol! Due to past experiences I don't think I will ever have another job done unless its permitted but laws are also different in different states and even counties. The kids I have doing drywall is from Alaska where no one does permits for anything ha ha!