Please make Sure when a person is signed up as Contractor his payment method is verified with in the next 30 minutes he signed in.Because know freelancers has to applied on those job post's also where payment method is not verified loose 2 precious connects and make sure contractor have to pay $200 as subscription amount to Upwork this will increase good reputation of Upwork. For both Freelancer and Contractor.
I think it's a bad idea. If it suddenly cost $200 to post a project, and every other freelancing site is free, clients would just go elsewhere. There would be a mass exodus of buyers.
Some would stay, sure, and it would probably make the site cleaner, safer and of a higher reputation... but they'd lose too much revenue. If your local supermarket introduced a $200 subscription, would you be happy to pay it?
Just on a side note... a contractor is a freelancer. Freelancer, contractor, provider, they're all pretty much interchangeable. You want clients, buyers, employers (at a push) for those who are looking to have work completed.