Voice over for Product Demo?

Hi,

I need to make a product demo video for a tool I am building, but I have a pretty bad French accent coupled with a fairly uninspiring way of speaking, which I know would be detrimental to the demo I want to make.

So I am thinking of hiring someone to voice the demo, or even do the whole thing with a video insert. The product is quite technical, so there is that too...

Does anyone know about a service that does this? And how much should I expect to pay for this (roughly)?