This issue has nothing to do with 'monopolies' or regulations 'preventing other suppliers from forming'; the drugs in question are too small of a market for multiple companies to bother making them, and none of them are under patent. So, the market shrinks down to just one supplier. Until some jerk buys the manufacturing line off and jacks the price up to unethically gouge very sick people for his own benefit.
The functional solution to this is for a government entity, or a university-based pharm manufacturing site, to take on the making of these 'orphan' drugs, since the free market has little interest in the investment to do so, because the ROI is too low.
If the government and medical insurers want patients to have inexpensive access to these obviously cheap, but lifesaving, drugs, they should be taking the steps to support that type of facility or project. Otherwise, this will just become a lather, rinse, repeat activity as other 'entrepreneurs' catch on to the cool formula used to exploit the orphan drug markets. Sooner or later, it will start costing insurers enough money to take notice, and then they'll have an interest to do something; it'd be nice if they had the cooperation of the government to facilitate doing it sooner, rather than later.