We are also planning to build a barn sometime next summer. I did get a number of quotes for a 36x36 pole barn. They came in at about 20-22 K, including labour ( assuming the site is graded and ready). Materials were about 8-10 K, and that is without any stalls, insulation, electrical etc. Roof trusses were quite expensive, and we would need to hire a "picker" to get them up on the roof. We are also looking into building a larger "lean to" style pole shed with one cantilevered roof rather than a trussed peak roof. Like you, I need hay storage, a couple of stalls, tack storage and space to get out of the elements when tacking up and when the farrier comes.
If you can work with central support poles in your structure, you won't need roof trusses, which should cut down on the cost some.
PaintHorseMares - is this what you did in my your barn?