Try this simple technique, using just basic html and javascript, no ajax needed either.
Use a Textbox, have all the items in your javascript in the page_load, and play with the data as you type the letters, the filtered results for the matching word will be displayed below the textbox, very fast. This is a pretty old article(asp.net 1.1 days), but this is exactly what you are looking for.
Google-Suggest Simulation using JavaScript in ASP.NET/ASP