The $23,000 probably have a capital cost of $30 per month or so, and if they're written off to nothing in 20 years (and the acquisition cost isn't lower by then, which it will), that's another $100 per month.
So that leaves $270 per month for maintenance, emergency supply and other upkeep. Seems completely reasonable that the actual costs will be lower.
Indeed, his uptime will be many orders of magnitude better than what the Ontario grid can provide.
It's an apples to oranges comparison specifically because it is the lines (and not the generating capacity) that fails very, very regularly in rural Ontario.
So that leaves $270 per month for maintenance, emergency supply and other upkeep. Seems completely reasonable that the actual costs will be lower.