You should negotiate about the budget with your client before accepting an offer and make sure that the agreed amount is fully funded on your milestone. Unfortunately I can't advice you accordingly for the case you`ve described due to lack of details. Thank you.
Do not concentrate on 4 people. Every freelancer has an individual contract with the client. You are responsible for only your contract.
Other's contract have no effect on it.
Also regarding Price:
You can ask 10 $ or 1000$, you are not bound to ask exactly 200 usd just because it is mentioned in Job post.