The main issue is practicality.
The vast majority of car buyers have certain expectations in terms of comfort, features and interior space which are pretty much essential in their choice of vehicle.
If you want to be able to carry 4 peopel in reasonable compfort and have the ability to carry a sensible amount of luggage then that imposes certain constraints on the overall layout.
The classic sports car is 2 seater, front engine, rear wheel drive with a low centre of mass and relatively short wheelbase ie it is designed for handling and performance first. These are the features whcih define its overall silhouette and body shape but also seriously impinge on interior space compared to say a fwd hatchback.
There are actually a few pretty decent sports cars produced in reasonable volume, things like the MR2 and MX5. These aren't particularly expensive but they still have the basic practical issues of any sports car.
So the problem is not cost as such but finding a large enough market to justify volume production for something which is inherently a niche product.
Equally even for customers who are prepared to pay a bit of a premium many will go for a high performance hatchback or a more luxuriously equipped saloon or estate.
Indeed if anything the market is skewed towards cars which look more bulky with high seating positions.