Hi Pajoube-
You know, if I had it to do over again, that is one thing that I'd definitely do differently - I'd build the trusses over the Winter (in an insulated shop/garage). Then I could start working outside in early Spring and be done by May or early June.
Since I didn't start building trusses until May, I didn't get started out at the site until smack in the middle of Summer and here in TX, the Summer heat can really sap you out.
If you're considering building a barn, I say go for it. There were really no big surprises. The only downside is that it did take a _lot_ of time. Enough time in fact that the money I saved probably didn't work out to be that much on an hourly basis. But I like to have something to keep me busy and with my new job (teaching) I have more time than I used to and less money so it was a good fit for me.
If you decide to go for it, feel free to drop me a note. There are a couple other small details that I learned that I'd do a little differently that I could pass on.
Best to ya,
Mark