Develop a website

I have an initial holding page for my website and I wish to have a more detailed and interesting site developed with the possibility of an e-commerce option, or a link to another site where products can be purchased. I woudl need the following pages:
- home / about
- contact details
- product ranges
- bespoke services
- trade - a trade log in site to be developed at a later stage but just one page to talk about trade options at this stage.


The content on these pages will need to be be updateable, ideally by me if it's quite simple to do.


Maybe a blog too? - please advise on what this involves.

I'd also like to learn costings on SEO as this is obviously key, but don't know where to start with this.

Please can you supply examples of other sites designed and set up and also a cost for the above.