Depending upon your requirement the cost would change, if your requirement is low the cost will be low and if it is high the cost would increase.
Domain is a unique identifier for you, for example "webkites.in" is domain name and it cant be taken or registered by others.
Domain name comes with various extensions like .com, .net , .org, .in etc where .com,.net are the top level domains and it costs high at present it costs around rs.660 and .in denotes India and it comes around rs.400 and rs.500
web hosting is a place where your files are stored.
Depending upon the hosting provider, a hosting with limited capacity for a period of one year will cost around rs.1000 and hosting with unlimited capacity is around rs.4000
SEO is called as search engine optimization and it helps you rank in Google so that it helps to increase the revenue of your business.
Depending upon the keyword, a highly recognized keyword will cost high and the vice versa.
Depending upon the requirement the time taken to complete a website varies.