Kexcelled TPU Filament Dark Gray, High Speed TPU 64D Flexible Soft 3D Printer Filament,1 kg Spool (2.2lbs), Excellent Elasticity,Fit Most 3D FDM Printers

Amazon-only with a wide SKU list: PLA through TPU, including silk and specialty variants. Prices sit at the low end; quality is consistent enough for general use.