I have a small PCB manufacturing facility and am in the process of building what you are looking for. It consists of a quality PCB with Atmel 89C53 and connectors for a 16 key pad and LCD. The PCB is designed to fit into a PacTec enclosure that comes with a 16 key membrane keypad, see it at

http://www.pactecenclosures.com/Plastic-E...VB-SP.html

I have a working model and can send you pictures if you wish. The above design is fairly flexible, let me know exactly what you need and we can negotiate. It will probably cost you less than you think and will probably be exactly what you want.