It's a bit of a 'how long's a piece of string' question really...
What features on the site are you after? Are you just wanting it as an advert for your company, just to get a presence online? Or are you wanting to sell things using your own shopping cart system?
The design itself shouldn't be too pricey, but I'm sure it easily can be.
The hosting also depends what you need. You can get half-decent hosting for �30/year. But if you want more advanced stuff, like an SSL certificate for an online store, you'll be paying more. Likewise, more visitors to your site will be more expensive, that sort of thing.
You can get decent free CMS systems that'll let you edit content easily yourself, so they should only charge you for either developing a bespoke version (maybe not required), or for customising an off-the-shelf app.