When freelancing I tend to work a simple system.

  £250:  An update to content - an evening or two's work.
  £500:  A tiny static site with some original design. <5 pages
  £1000: A full static site for a SME. Full Design. ~5 pages. 
  £2500: As above with some dynamic elements. ~10 pages.
  £5000: Medium dynamic site. ~20 pages. 2-4 weeks work.

I then slide upwards for jobs I don't want and down for people I like. I've never gone above £5000 for a 'homer'.

I also have a mate-rates scale that appears below this:

  Free: Family. Charities I like. Updates + tiny static.
  Bottle of Wine: As above but close family friends.
  Bottle of Whiskey: As above but good friends.

If I get a request for a bigger job from friends or family I tend to pass them on to a developer chum these days — experience has shown it's for the best.

Having a fixed, doubling scale like this works well. Each next price needs to be big enough to make a difference to me as I am essentially very lazy and I like my free time. Also, I am a terrible soft-touch and would probably charge everyone mates-rates if I didn't force myself to do this.