We figured out that overhead power lines would prevent it from being lifted in by a crane, so we decided to have it assembled onsite. Then the county decided -- after full approvals -- it needed a concrete foundation. We asked how to do that when the backyard already had a concrete foundation. Building department said pour it on top of the existing foundation.
I've mentally blocked my memory of the other ways the county came up with to make it hard to place this cuboid shape in my yard, but each time added another $10K. And the end result, other than being a foot off the ground because of the duplicate foundation, was nothing more than the $30K structure I originally bought. I can't point to where the extra $50K went and say at least I got value from it.
Like all home construction or remodeling, each misstep was outrageous, but tolerable because it was surely the last hiccup before completion. Only later do you realize it's Zeno's Paradox and you're always halfway from the finish line.
Whoever your contracter was doing paperwork screwed you.
$33K list price 4K delivery 3K sales tax 8.5K onsite assembly 1K building application and permit
So that's $49.5K for what in my mind was a $30K prefab office.
Then a basic wood frame foundation for a couple grand, torn down when the county changed its mind about the foundation type (but I did end up using most of the wood for other projects), a $4,500 site plan demanded by the county now that their concrete foundation made the project look more like a permanent fixture on the property, additional permits for the foundation, changes to the site plan when we discovered the existing foundation under the backyard pavers, and then building the foundation and the framing atop it, which all in totaled $70,485 -- not the $80K I remembered.
So I started with "Ooh, an extra room for about $30K?! Let's do it!" to "Ugh, it's actually going to be $49K with all the tax and delivery and permits," to "Aaargh, $20K more because of errors or crazy shit that they could have told me from the start." Yeah, maybe the contractor used the foundation change orders to sneak in an extra $2K-$3K, but I'm not a GC and by that point I wasn't going to bid it out.
But, as I said, I love the office and use it daily, so I can't say I regret it.
Overall the price you see on the website is the price for the unit. You need to factor in delivery, upgrades, installation and site design).
As mentioned, it wasn't a cheaper option, but rather a better investment with the quick build and quality control. Our total for the build (with land) was still a savings compare to what is available in our local market.