I used Willis Custom Homes to build my barndo.
http://willishomestx.com and I am a very satisfied customer.
Regardless of who you choose, make sure you know exactly what you want! I paid a lot to have 15 foot wide, concrete, covered porches on three sides of the 40 x 80 building (house part inside is 40 x 30, two story) and I am thankful every day that I did that. Once they get started, it doesn't take very long at all! I am handy and am doing all of the inside building except plumbing that had to be done by a plumber (gas lines) and some of the electrical. If you plan to save money by doing some of the finishing yourself, be ready for it to take three times longer than you thought and be certain you are willing to do it!
Under the 'Our Work' is listed a brown and white barndo in Snook. That's mine!