Chart/Graph implementation for Wordpress site

Our Website [login to view URL] has market graphs, but they don't display well on some browsers (mostly internet explorer). Also the data is time consuming to update. We need a new solution. Overall we are happy with the layout and appearance of the chart pages. Example: [login to view URL] We want an interactive solution, similar to the existing plug in. We don't just want images/charts copied and pasted in from excel. We invite you to put forward a proposed solution, together with a cost to implement the change. Please allow for updating all the site pages with charts and entering all the data which is currently displayed (we have this in excel format and would provide that to you). Your cost should include the cost of the plugin (if applicable). At present we only display line charts. However may look to provide other data which may require other types of charts. We update the charts every two months, so it needs to be easy to update. Please clarify in your application: Your proposed solution. The reason why you have chosen that solution. How easily the charts can be updated from an excel spreadsheet. Your timeframe to complete the job.