Power Supply for stepper motors

I am building a Halloween prop that is essentially a classic flying crank ghost, except the original design called for an extremely slow motor turning a "crank" that had three elevator lines attached, as it rotated the crank got farther then closer to each point respectively resulting in the suspended ghost prop going up and down but the three points of contact each moved at their own interval. It was cool but has a very distinct and rather boring pattern. My plan is to lift the three points independently using stepper motors. I purchased several 28BYJ-48 stepper motors and ULN2003 driver boards but quickly realized they had neither the torque or speed for the task. I now have three 17HS4401 NEMA 17 stepper motors and L298N driver boards. However upon testing the units I'm finding I need a different power supply. The motors are apparently rated for 12v. I had a 5V 8A power supply that I planned to use with smaller motors but it's not adequate for the new ones. I have a 24vdc 10A power supply that I tried to use with XLE6009E1 DC-DC converter but it appears it can only increase voltage not lower it, as I was able to increase the voltage with the pot but turning in the other direction only lowered it to 24.1V and eventually I realized I was letting the smoke out of that device. When began searching for a 12v power supply I stumble upon a website circuitspecialists dot com which states "Stepper motors will run better when the voltages is several times higher than their rated voltage"

I'm just looking for a power supply that doesn't break the bank that I can relatively easily use to power the 3 stepper motors through the driver boards controlled by an Arduino Uno.