Horses take a lot of money, close management, and a ton of work. Even finished horses need the same basic necessities as unbroke horses: the right food, turn out, halter, ground manners, access to water.
Now you have to figure out what food to feed. Maybe the grain or hay you select for all of them doesn't work for one or two, then you have to find a new feed. That water trough with water that they require will have to be dumped and scrubbed at least once every 2 week so that it doesn't get disgusting.
Then you have to catch them, groom them properly so they don't get rainrot or thrush, which are both PITAs to get rid of. Then you have to have a farrier come that knows what they are doing, to trim those hooves.
But to even get to that point, they need proper ground manners which takes a lot of work, even if they are "trained" because the owner has to know how to read body language and respond, or how to properly catch/handle them.
And this is all before you can even get in the saddle, because you have to find one that fits, and then you have to find fitting tack, and the right bit for your horse. And they need to be ridden properly so their muscle comes in right.
And you're getting 3, so it's going to be a lot more work than just one.
"Strength is the ability to use a muscle without tension"