I like ebay. If you are cheap and patient like me you can get awesome deals. People are always selling bike stuff that is barely used.
I dropped about 2 lbs off my road bike for only $75 after buying and selling stuff. Pretty much all the $75 i lost was in seller fees. I saved somewhere between $800-1000 for basically new stuff

Non cycling related: I also just bought a $900 multimeter for $110. Was pretty much new.