In my experience buyers are looking for quality. Why would someone buy your average model if someone else has loaded a better quality one? A few buyers may be motivated by a lower price on an average model, but in my experience, there are not many such buyers. In fact when I experimented with lower prices, I was getting less sales. Presumably low priced items scare customers off because they think there is something wrong with your model, or it's pirated, or something.
All large quantities does is clog up the search system. There are thousands and thousands of average or low quality items on this site already, adding to those will not get you sales.
Having said that, quantity is important. The more models you have, the more views, the greater likelihood of a sale.
So IMO, you should be aiming to make the best quality you can, but not by add ridiculous amount of days to the development time. So a steady flow of high-quality items is my advice.
And if in doubt, quality over quantity every time.
