Is It Safe To Use Debrox, Mineral Or Sweet Oil For Wax Build Up In A Cat’s Ears? Tresaderm Is Now Too Costly.?

I have a 9 year old Ragdoll that has oily skin, and has always had increased wax build-up in his ears, compared to other cats. If none of these items are safe to use in cats, could you please recommend something less expensive than the Tresaderm that he has always used?