The model looks ok to me. 9k polys is perfectly fine to be considered "low poly" these days, and should be relatively easy to rig with modern rigging tools in most software packages. Since you're offering the native .blend file, it would certainly help sales to include a rigged version if possible, and since it's a low poly model, optimizing it for the Eevee render engine might also help sales for many Blender clients. Eevee PBR materials usually convert quite well to Cycles, but not always so the other way around.
Offering the "high poly" version along with the low poly is also a good idea, and should also help sales, especially if the high poly version can be 3d printed. Even if it can not, it should be fine to include it and should not impact the low poly tag. You can offer it with the low poly model as a download option (STL), that's a good way to do it.
