It is not that N or C are overpriced. It is that all prices for DSLR have come down a lot since 5 years ago. Brands like Sony, a big corporation with a lot of muscle, is trying to gain a foothold (market share) in this industry, and they chose to compete aggressively in the entry-level DSLR market but pricing their products substantially lower than their competitors' offering.
N and C will always have their supporters. Why? Because it is shown that once users start buying lenses and accessories, switching costs will be high for DSLR systems. So the tendency is to stay within a system. And with a lot of professionals in publication, news, sports and adventure industries deeply entrenched in N and C systems, they will always be popular due to recognition. Why? because the top range of N and C are just that good and if you have a wide user base in the top target segments, it is easier to make top-end products and sell them well.
Each system has its pros and cons. Canon has very aggressive lens line up and N is very backward compatible and has tons of legacy lenses that can be used since the 70s. Sony and Pentax are actually pretty good with in-body stabilization and value for money. Olympus is famous for their very good color reproduction, dust management, and its incredible and unbelievable weather sealing (E-3).
In the end all systems are capable of producing exceptional pictures, and give your skills enough room to grow for a long long time. I would say the camera systems are not a limiting factor in you making good pictures. In the end, the limiting factor is your skill level. So it is up to you to go try them out and see what you like most. Buy with confidence.