Hi I've got an ELM327. I got it off e-bay. I'm sure it was only about £50 came with loads of software and took less than 5 minutes to install onto my laptop. I've used it a couple of times and read a couple of owners on this site with it, one just a few weeks ago.
Here's a link for the one I got seems cheaper than it was a year ago less than £40 delivered.
http://cgi.ebay.co.uk/Car-Code-Error-Reade...%3A1%7C294%3A50
Hope this helps.
Mike