Cheap squat racks can be safe if you use them properly and don't load them beyond their listed max weight capacity. However, they may be unsteady when racking or unracking the barbell, as they are typically made with thinner steel or weaker materials like aluminum. If you plan on lifting more than 500 pounds frequently, a more expensive squat rack may be worth it. It will typically consist of heavier-duty materials and remain more stable as you use it.