You could also use a desktop with one of these ATX power supplies that runs on 12VDC instead of 120/240VAC:
How much trouble shooting does it eliminate?
How much experience does it make unnecessary?
Or to put it another way, at the point where 1500w of 12v source computer power supply makes sense, the price is not unreasonable.
Price sensitive shoppers are not in the product's market segment.
Anyway, these kinds of converters can usually regulate themselves.