hi,
I would like to provide my services for this requirement of yours. As you see in my profile, I am currently developing a web based application for a new york based mobile phone company - Aerotel. Amongst the various features, one is a template based invoice creation in excel. Your requirements are very similar to the same and i think i would be well suited to take up this assignment. Please let me know if you need any more information and i will provide you the same.
Regards