While you want to be careful not to over-improve a house for the price point and prevailing market, you still want to put in quality materials. Quality materials can be found at various price points. No one wants to put inferior materials in a flip and end up with a catastrophic failure in the structure or materials that ignite and burn quickly in a fire. That’s why flipping is not meant to be done by weekend HGTV watchers. It’s also why there are inspectors who come and check the work along the way.
People who flip regularly for a living undoubtedly have relationships with vendors and can get materials at much better prices than the accountant who flips on the weekends for a hobby and dips into Home Depot to pay retail for his plumbing fixtures and cabinets.