Today I started a Grand Exchange noob and ran her to Varrock and into the Grand Exchange.
Along the way I picked up bits and pieces of things that others had dropped - logs, bones, meat, etc.
When I got to the Grand Exchange, I listed 2 of my meagre inventory bits in their F2P slots at max rate and logged out.
One day this noob will be a millionaire, just from merchanting in the Grand Exchange!
Follow my adventure :)