Less than 1 week –
Less than 10 hrs/week –
The simple and quick task is to move the non-core modules out of the core module folder from a drupal 7 sites. You must disable them all, as well as any core modules they are tied to), move the modules to the sites/all/modules folder then re-enable them.
I know that it is a quick job so should take you one hour at the most, likely much less, so this is a maximum of $10.
The freelancer should ...