In a low-frequency inverter, the transformer is the heart of operation. Every parameter needs to be correct, and it has several parameters. You (or your technician) can expect to test many trial assemblies, before you have improved it sufficiently so you can market it. The goal is to avoid having your inverter break down in the customer's home.
A high frequency inverter can use a smaller, less expensive transformer. But then you need to apply greater knowledge and expertise, to develop a unit that can be marketed.
There are the technical factors. Then there are the real world factors.
Examples:
* Customer's ability to operate the inverter correctly.
* What safeguards you must install to prevent overloading, short circuits, etc.
* Ability of inverter to withstand wrong battery polarity, water damage, high voltage spikes, etc.
* Ruggedness of unit during shipping and handling.
* Your cost for units to be shipped.
* Your cost for defective units to be returned to you.
* Regulations. Such as, whether unit will still operate after being dropped 3 feet?
* Your own ability to make good on warrantee.
Some things will be easier when you make the unit lightweight.
Some things will be easier when you use simple construction.