Plastic fan blade for DESA gas heater?

I have a DESA LCR30NT unvented infrared gas heater. The plastic fan blade has disintegrated and DESA wants $48 for a new blower assy. Are there any sources for purchasing these small plastic fan blades. I do not have a spec on the blade, but it is 4.75" in diameter and has a 3/16" centershaft. It mounts simply by pressing it onto the motor shaft. I would appreciate any info.