Differences Relay System and PLC System

I will explain the differences in the Relay System and a PLC System in the same application. I will analyze the cost to make the Relay System and PLC System used for the same application.
For example Diagram Relay and PLC Ladder diagram that I use as follows:

1. Figure Diagram Relay






For each of these diagram requires the following components:
1. Components that are used for Diagram Relay and the price (Approximate)
a. Price Analog Timer, approximately = $49.63
b. Price Timer Socket, approximately = $9.37
c. Price Relay, approximately = $10.89
d. Price Relay Socket, approximately = $6.30
Total price for the Relay System, approximately = $76.19

2. Components that are used for PLC Ladder Diagram and the price (Approximate)
a. Price PLC, the most expensive, approximately = $250
Total price for the PLC System, approximately = $250

Conclusion if viewed from the price of its components:
1. for a simple circuit like above then for the PLC System is more expensive than the Relay System.
2. Circuit mentioned above is a simple circuit, if there are 10 times as above circuit then:
a. The price for the Relay System is 10 X @ $76.19 = $761.9
b. Prices for the PLC System is fixed = $250

So my advice if you should use a simple circuit then use Relay System, but for a complex series should use the PLC System.