When sourcing recycled polyester felt (rPET felt), price is primarily driven by density (GSM - grams per square meter) and thickness. Buyers should verify the fiber fineness (denier), as finer fibers result in a smoother finish but may increase costs. Additionally, ensure the recycled content percentage is clearly stated, as 100% rPET felt may carry a premium compared to blends. For acoustic or industrial applications, check the NRC (Noise Reduction Coefficient) and tensile strength to ensure the material meets functional requirements.