I have never been a fan of using freelancers over full time workers, but I my case it was excellent choice. in Trustisto we have bunch of e-commerce plugins for PrestaShop, Magento, Woo etc. Each one needs different skills set. While I have all created by myself, keeping them up do date is a pain. So now I am using UpWork to make changes in my plugins. Its 50-100 USD per job.