Few to keep in mind with pre-engineered steel buildings:
Increasing pitch does not reduce loading, meaning a 4:12 does not reduce the load criteria anymore so than 1:12, from a lbs PSF perspective.
4:12 will NOT eliminate ice damming at the gutter, potentially causing much greater issues with water penetration at the eave, using PBR roof and wall panels.
4:12 is mo money, considering colored roof is almost a must and frame sizes increase beyond lesser pitched, again, because pitch doesn't lessen loading.
Based on experience, the best manner to approach is finding a local metal building contractor.
They are typically adept in building criteria, can offer basic general contracting services, say floor, shell, doors, itch, for less than what a DIYer can, provide a better finished product in a fraction of the time.
With concrete averaging $100 a yard in the southwest, that would not get much of a poured floor.
In the same geographical area, with minimal footing requirements, going rate on finished floors and footings is ~$4.25 PSF on jobs ranging for 2-4k SF with basic 4" floors and 12"x18" footings.
There's no different model for any loading requirements, regardless how marketed, since each geographical area dictates distinctly different and buildings are pre-engineered accordingly.
They, like others that market to the DIYer, typically market varying degrees of trim packages that increase in cost, accordingly.
Not throwing them under the bus, because they're, by far, the most successful in the niche market they service, but it's common practice to put a cheap price on a website, one that includes just about enough to call it a completed shell, but lacks the fit and finish common the industry standard.
Not saying it's deceptive marketing, because it is the consumers responsibility to be informed, but base trim packages aren't typically gracing the front page of the website, plus many DIYers don't know the difference in the actual products, anyway.
Where one has to be cautious as a DIYer is reading the fine print on the contracts, from what IS included, to even adding freight and sales taxes after the fact.
Unsolicited advice to any considering is to find a local metal building specific contractor that had projects that can be driven by and visually inspected, that can handle the foundation and building shell to a "dried in" state. ( use your own licensee trades, if you wanna save the typical 20% GC fee )
Finished product quality will far exceed what a DIYer is capable and for a lot less money, regardless the cheap prices for materials you'll see on the internet, since they're but a fraction of completed costs anyway.
