jQuery Autocomplete is a great jQuery plugin for developing efficient autocomplete input fields. I used this plugin in an MVC preview 5 application to build an autocomplete input field that fetches the data from a database and passes the result to the front end in JSon format. Following these steps, you should be able write your own autocomplete input field in MVC.
The last couple of days we have been trying to get JQGrid working with ASP.NET MVC. It turns out it is not that hard to do. You just have to be cery careful with the javascript you put in the page, because if you don't do that nothing will happen.