What makes you think a republic is cheaper? Presidents receive salaries and life pensions. Security needs to be in place for Presidents and their families, even after they leave office, There is the cost of elections every 4 or 5 years. Official residences need to me maintained. Staff has to be paid for. Official travel needs to be paid for. We know for instance that the costs of the presidencies of Germany and Italy both exceed those of the British monarchy. I dont see how a monarchy would be more expensive, in fact it may even be cheaper since there would be no elections and no pensions for a monarch.
Oh, presidencies are not cheap. But they are people, who have worked hard to reach a goal. They weren't born to the "manor" so to speak. First of all, the British Monarachy costs a fortune, always played downed and dwindled into some bizzare figures, that belie the living arrangements of the family. Remember, they, believe, that all the land, jewels and other accoutremounts, are theirs, because they were born into it. Do you think the queen pays for travel for business. Do you think she packs a bag or gets on a commercial plane or does anything remotely necessary to cuts costs. And then she goes and skes hands. Her Prime Minister is reponsible for government. It is live theatre. Each of these nations, Italy, Germany, etc. have Prime Minsters and, actual, pepople, who, really, run the government, that work, put the behinds on the line for good or bad. There are great costs to that, besides other costs that keep a monarch in the style to which they are accustomed. They travel and live, too and are paid, too. So do the British have Prime Ministers, who get paid and travel. So, besides keeping a monarchy, they pay for a "real" government. Double. No one counts that.