Ecommerce website construction
 

I need a person/company to build an e-commerce website. This should include at least:
- checkout options using major CC/paypal etc. (opus?)
- email forms
- ability for customer to create user accounts
- security (trustwave/trustguard/verisign/mcafee?); SSL certificate
- reliable host and backup
- coaching for other administrative users to intuitively modify content and upload pictures
- SEO
- dynamic reflection of items in stock

I noticed online there are services such as Volusion, Shopify, and Bigcommerce. Any input would be greatly appreciated.