Hey, I make my own shampoos using ingredients and recipes from Hobbythek. I love them, with these shampoos I got rid of my dandruff and my hair stopped being oily. I totally recommend it !
If you live in a small town, you can also get the stuff online from Jean Pütz Produkte
But check first if there is a store in your town.
They also sell ready-made shampoos which are a bit pricier. But making my own is pretty easy, it takes me a few minutes every few months. And it´s fun to customise the scents and ingredients.
The first time you might have to spend a bit more money (I spent 20€ for the ingredients, because you have to buy bigger quantities than you need to make just one shampoo) but some of them you use very small quantities, so after 3 years there is still some stuff that I haven´t repurchased.