You are right in thinking that large heavy items can mean larger profit margins and less competition, but there is more work required.
If you have an account with a freight company, then what they actually charge you will be much less than the quotes they give you if you call them out of the blue for a single piece of freight. Often it's 25-50% of the quotes they give for non-account holders. If you regularly ship freight with the same company, costs will be lower. Business to business is also less costly than if any residential addresses are involved.
At my work account we have a warehouse with a loading dock and plenty of shipping supplies. We routinely ship LTL, and have accounts with multiple carriers so can compare bids and go with the lowest bidder or most reliable service. Often freighting a 100-150 lb item is cheaper than UPS or FedEx ground services, and it's almost always cheaper than breaking up a shipment into multiple 100-150 lb packages.
At my personal business, I do not have a loading dock. When selling a large bulky item online I offer free local delivery within 50 miles and a delivery charge within 100 miles. A lot of large equipment buyers prefer to use their own freight accounts to save on cost and to get more reliable service on their end, and I have done this a couple of times over the years. If I absolutely must freight ship something, I deliver it myself on the "first leg" to a freight terminal, either with my own truck or with a rental truck. This saves on fees and complications of the first leg (i.e. liftgate fees).
Having a service build a crate and package a large item for you is very expensive. You are almost always better off building your own or salvaging a crate from another shipment.
