Here's an interesting web site from Tulane University which discusses the issue of currency devaluation during the reigns of Diocletian and Constantine. A numismatist will find this site particularly interesting for its tables indicating the metal content of coinage; brief passages from Diocletians Edict of Maximum Prices help us understand the cost of commodities.

It is important to note that Diocletians wage and price edict effectively failed to solve the problem of spiraling inflation during the fourth century, and probably disrupted trade much more than aided it.