add some render and wireframe pictures here in this forum. It is impossible to evaluate your work without seeing your model.
I am not familier with sketchup but I must say that 37 millions of faces is horribly high number and I wouldn't be able to open such hyper-high-poly model. But I don't know how complex your model is.
And also in space category (space shuttles, spaceships, orbital stations, buttle ships etc.) there is a big competition and there are a lot of high quality models of cheap price. But if your model is unique in some way (design, extreme quality) than it can have higher price.