img default address

Is there any way you can change the default url in the img insert box when making a post?
For instance – it defaults to http:// but I would like to make it default to http://www.mysite.com/my-images mainly because I rarely link to another site for images and it becomes tedious typing in the address each time.
Lazy – I know, I know – but if I can make life easier – I will every time!