Setting up a fairly basic site isn't that difficult - you need to have some web space to host it, and if it's a business you might want to get a Domain Name (the pooliebunker.co.uk bit of a web address) and point it at the site.
Adding eCommerce on is a bit more involved. There are packages out there to help you do it, but they can cost and usually you'll have to go with a dedicated web host who will charge you a fee per month - someone like 1and1.co.uk . If you need someone to design and run it or you then there are companies like Durham Associates -
http://www.da-group.co.uk/ (who are actually the people who run Sport Network, not necessarily cheap but localish).