I need shampoo both for oily hair AND fragrance free but I don't have money to constantly try new products, anybody have any recommendations (please do not recommend if the shampoo is not both for oily hair and fragrance free)

Ever since I was diagnosed with a fragrance allergy, I've been having a hell of a time finding a shampoo. A lot of fragrance free shampoos are also "gentle" which don't work for oily hair. I'm so broke right now. I've tried making some shampoos, but that hasn't worked. I just need something that is budget friendly that is fragrance free and actually works for oily hair. DIY or store bought is fine, but I really need the cost to be below $15 if possible.