Just going to follow this for interests sake....
In 2005 I started a 28 x 30 x 10 attached to a 32 x 30 x 12 building with one 60' wall. I scrounged rafters and built about seven of each size to get the length of building I wanted. Hence the two different widths. I paid regular price for all my lumber as I didn't have time to look for sales. I bought a semi load of random length 4 x 6 black treated posts and installed them on 4' centers. ($500) Hence the two different heights. I bought 2600 sq. feet of random length tin from a friend of mine that he got on sale. ($600)
I had help with half the rafters and half the roof tin. The rest I built all by myself. The walls are a layer of tar paper under house wrap covered in a board and batten style rough cut 1 x 4. All in all I have about $7500 + labor into the building. I still need to build a door which will be about a $1000.
I think the key is looking at something you want to build so you have an idea of how to do it. Many out there can't see the end product so they don't know where to start. Before building my barn I looked closely at how my brother built his pole barn. I thought " I can do that". I built a detached garage 36x36 a hay barn 21x36 then the barn 57x72 they are all built from the same basic pattern, never had plans for any of them. Trust me I'm no framer, just a backyard hack. They all worked out very well for their intended purposes.