If you can't decide which one is for you: Garmin 305 or Garmin 405 you may look for some inf on this site:

http://garmin-305-review.com
http://garmin-305-review.com/garmin-305-vs-405/

Those two units are conceptually different so you need to check their features good before you decide which one is best for you.

Here are links where you can buy Garmin 305 Forerunner:

http://www.amazon.com/gp/product/B000CSWCQA/ref=as_li_tf_tl?ie=UTF8&tag=mirjamitropho-20&linkCode=as2&camp=217145&creative=399377&creativeASIN=B000CSWCQA

And buy Garmin 405 Forerunner:

http://www.amazon.com/Garmin-Forerunner-Water-Resistant-Running/dp/B0011UIXNE/ref=as_li_tf_ssw?&linkCode=wss&tag=mirjamitropho-20