Look for kayak racks. They’re usually designed to handle things with large wind resistance so naturally, they’re built heavy duty, and sometimes they’re actually cheaper than specific “ladder racks”.
The first guy I ever worked for back in 94 used to drive a Mitsubishi Colt tiny little car and he used to strap the ladders straight to the roof, the back doors would not open as the rope was preventing the doors from opening.
One time he strapped a 30’ ladder to the car.
He also put oil in every time he put fuel in it, as it smoked more than a chimney.
A great experience that was to learn what not to do…
Write on an envelope marked as 'ROOF RACK" and put $40 inside each week, after 7 or 8 weeks time you will have the cash to spend up to $300 for a sturdy roof rack.