Forms :: Validate The Text Property Of My Combobox

I have been searching for an easier way to validate the text property of my combobox.

Below is a background of what I am try to accomplish:

I have a from that contains many controls, mainly comboboxes that are bound to datatables. I have these set up in such a fashion as to when the user begins to type, the values begin to show and auto populate the combobox. This makes the selection process easier to select an actual value in the list. But, as we all know, you can lead a horse to water but you can't make him drink. Users still have the ability to type something that is not in the list. I do not want to allow them to leave the combobox until the have selected or typed a valid value from the list because I am building a SQL query to retrieve data for a later form. I don't want to lose the above mentioned functionality of being able to type it in. I currently have it working as follows, but there must be a more elegant way to do this.

I first populate my combo box like so:

CODE:

The part I don't like the most is that I feel like I should be able to use the list already loaded in the combobox data, but I can't figure out how to do it. So I end up having to reload it, this seem like a waste of time.