Hand your husband a washer and go to it. Washers don't turn, they are flat pieces of metal with a whole in the middle.
The reason wheels are expensive is because you get what you pay for. They don't need washers, they need bearings. And if you need them to ideally be sealed to keep the wheel in working order after being on contact wit dust and shavings, etc. Firstly finding a large enough anything that right shape to make a wheel is difficult and expensive. Then you have to drill through it and make sure that everything is mounted EXACTLY in the center, otherwise the wheel will wobble, the bearings will go out in a very short time, the turn will be inconsistent and choppy which would be uncomfortable for the chin and shake the cage to all ends.
You can get a good wheel for usually $60 - $80, if your chin lives for 10 years that's only $8 a year. You have two that makes it $4/chin/yr.