If an entity wanted to gain a significant share of a PoS network, they would need far less money than would be required to purchase enough mining equipment to try and gain a significant share of a POW network.

This would have an impact on the price of the PoS coin, for sure, but it would still pale in comparison to the physical costs of trying to compete as a miner. Not just capital expenditures for hardware, but operating costs as well. Buying a PoS coin is all that one needs to do in comparison.