Your materials, your yarn, your beads, your fabric, thread, you know all the things that you need for your individual projects. Materials are one of those ongoing purchases when it comes to crafting. For every project, you have to find the right the color material, the right weight (for fabric or yarn), and the right shape and size (beads).
You can try to buy used but finding enough yarn or fabric for the project you need can be difficult. Not to mention finding the right color, shape, size, weight, etc. This is one category where I would not fault you if you only bought new.
Buying all new materials can get expensive, especially if you have to do trial runs an such. Save as much as you can from project to project. You’d be surprised how little fabric you need to make an applique or even to quilt. Then you only buy what you absolutely need for each project. I find that a spool of thread can last two or three projects especially neutral colors like white, black, and tan.
You can, also, be very diligent about checking clearance sections, just be aware that clearance sections are items that the store will not carry anymore so grab as much as you are going to need because getting more may be difficult.
When buying new plan your project well ahead of time so that you can scope sales and coupons. Nothing like having to pay full price for a last minute costume (i see that one a lot). Planning ahead also gives you a chance to do any practicing and trial runs on cheaper or leftover materials so you don't mess up your more expensive materials, and then have to pay full price last minute for new material to start over.
Materials will always be a recurring cost but planning ahead and buying on sale will make it less daunting.