One-time geocode of 300k street, city addresses

I have a list of about 300,000 addresses consisting of:

- street address
- municipality
- province

I would like to find out the latitude and longitude for each of these addresses.  I also want to do this in advance for all addresses, rather than do it as-needed.  

Any ideas for the best way to accomplish this?  

p.s.  This large number of addresses to be geocoded will be a one-time occurrence.  I won't have to do a large number again, but I will have a need to geocode single addresses one at a time as they are added in future.