Your logic is flawed. If you want to provide exotic guns, you can't expect to have the same volume of sales as the other manufacturers that cater to the M4 crowd. The M4 models are offered in such volume because there is a demand.
The reason your Tavor and many others are more expensive is that there is lower sales possible and a higher risk to produce them.
If you are going to make new guns, don't expect to be able to sell them cheap.
As for a general grudge against the M4, why not produce the really rare ones? Try to find a Shrike and come back telling us that they are easy to find.