The two factors that make it challenging to start production in a market, more commonly known as barriers to entry in business term, could be as following:
Product differentiation
Existing firms have officials identification of the goods brand and consumer loyalties. Therefore it is difficult for a new firm to entire a market with a new brand and to gain customer loyalty.
Capital Requirements
The financial resources needed for the foundation, machinations, Research and Development, latest Technology and Promotion of the brand of a market. Capital Requirement is also a factor that could make it difficult for new firms to enter a market.