re: "We need an estimate of what is might cost to find a stable Calendar plug in for our website."
This isn't really something you can do effectively in the Community Forum.
Post a job description of what you want done. Post your job on the main site at http://www.upwork.com
Be very clear in your job description that you would like an estimate of how much time it will take or money it will cost to do this. Posting a fixed-price job may be problematic, because you will be required to specify a dollar amount. And YOU DON'T KNOW the dollar amount. So if you put down $100, most people will probably tell you $100.
So it may be be better to post an hourly job.