I agree with @jaguarbeastproduction and @LemonadeCG
To answer your question:
Yes sometimes some products are sold 4 times per year, sometimes 40. Depends on the market demand and quality.
Here is some technical with your models:
- Renders with noise
- Uv/texture scale & fidelity
- Lighting/shading. A standard white ramp photographic style background looks nice usually always.
- Complexity. We are trying to save an artists time by providing something of value, thus the price reflects how long it takes. So if you can save the artist 5 hours at an average of $50 per artist hour, then $80 sounds like a good deal! (for both of you if its a good product and return sales).
- Provide Value. Pretty much explained in my previous point but it is a point of its own.
Renders with noise shows that you do not care enough about the product to spend the time finishing the image. If you were in a fruit shop would you buy the apple with the bruise or the perfect looking apple? Your product's appearance is important.
3D Model Descriptions are short, whats the materials used, where are they sourced, pbr/photogrammetry? What texture formats are delivered roughness or specular workflow? Whats the dimensions of the object, What is unique about this purchase? Why is there no native file format? 3dsmax, blender maya? (if you look at the statistics you can get a good idea of what formats are highly requested). What software/render engines is it compatible with?
Most importantly, how are you saving people time and effort? Have you researched your market and asked people what things they need on a daily basis or how you can speed up their workflow? It might be worth a Direct Message or two.