If you're looking for free stuff then there are some obvious sources that don't really require much in the way of personal contacts.

If there is kerbside hard waste collection in your area then check what stuff people put out... desktop PC's, TV's etc.
If there is a decent size Salvation Army store (or something similar) nearby (usually the main one as it will act as distribution centre for the other smaller locals) then do some volunteer work and you can get free stuff if the manager is cool about you salvaging stuff they throw away (in my experience desktops are rare but you do see laptops).