Like Jamel said, go to the muncipality office in town - 1 Church St. You need to take a sketch of the barn (my builder provided me with this - done on AutoCAD or a similar program) with he demensions and I think a sketch of the property and where the barn will be located in relation to the road, house, well, septic and property line. Are you building a loft or 1 storey? Anything over 13 ft in height (if I remember correctly, it's 13 ft) will need an engineers stamp so go for a 1 storey with hay storage on the side if you can. That's what I built at my old place in Shubie. I probably still have the plans kicking around somewheres.
Then you have to pay the fee (based on square footage) and they will mail you a permit.
Who did you get a quote for for the labour?