Freelancing is a lightweight plugin for Build a Crowdsourcing/Freelancing platform in WordPress using WP Job Manager. Being shortcode based, it can work with any theme (given a bit of CSS styling) and is really simple to set up.
Freelancer can give Proposal or Bid
The client can see all proposal and choose
Store Owner can charge like Upwork/elance etc
The client can post a job as fixed price or hourly