300 words. Please see the attachment.
1. Is this an example of a perfectly competitive market?
This is not an example of a perfectly competitive market. In fact, this is an example of monopolistic competition. The reason is that each competitor has its own distinct web design, brand name, and graphics. Each retailer attempts to differentiate her products as well as her website. Even small retailers spend some money on advertising their sites. In case of a monopolistic competition there are many consumers in a given market, and no single market has total control over market price, there are few barriers to entry and exit, consumers perceive non price differentiation, and the sellers have a limited control over the prices they charge (Brakman.S, & Heijdra, B, 2004).
2. Would it be difficult to calculate MC and MR for these small online retailers?
It would not be difficult to calculate the marginal cost and marginal revenue for these small online ...
This answer provides you an excellent discussion on competitive market