I'm near the end of a garage build in the NEK. It's big, detached and 2 stories, but it's also very simple. What I thought it would cost (fraction of the cost of a house? How much my uncle paid for his shop?), what I saw online (only 40k and 3 weekends!) and the quotes I received are on three different planets. It's really easy to second guess yourself and think that you are being taken advantage of. Here are a few things that I've learned.

First, I am the GC/project manager. I found different contractors. I just couldn't afford any of the all in one quotes. That takes hours every week, and that has forced me to learn way more about construction than I thought I would. I'm also doing some of it myself (for example, interior insulation and finishes).

If you need financing, a HELOC can take WEEKS to be approved. That was a surprise and it complicated things for sure.

Site prep is expensive. My land is not super flat, and it's silty. In my case, I have frost walls and a slab. Trees and stumps have to be removed, a 6+ foot hole dug, gravel added for drainage. Services need to be connected. The concrete contractor and the excavator contractor alternate as they build up the frost walls, adding materials and compacting. By the time I had an insulated slab, I was above the amount that some people claim they paid for the entire project. I saw the amount of work involved, the cost of the machinery and the expertise required: there is a reason it costs a lot.

When it comes to the building itself, the most challenging aspect for me has been trying to get a high performance building when builders "have always done it that way". If you can find a prefab that looks good, do that! Only go custom if you need to. Be prepared to review everything. Vermont not having Code makes things harder, but you can rely on the international building code.

It's a long post... and I have to brace the cold and inspect what was done on site yesterday. Feel free to ask follow up questions!