Thanks for the responses.
rgam - I appreciate what you are saying. I think it is roughly what I am doing now, but it is a bit clumsy in that the user (of a financial application) will typically have a list of regular customers to select from, and also may have other customers that are one-off, or infrequent which they will not want to clutter their options list with but still need to record against a transaction.
Ryan - thanks, the datalist looks like it might be right option. I will look at custom widgets.
All the best - Phil