Never waste your money on expensive pesto/basil pastes. It is the easiest thing to make and keeps frozen for up to 2 years.
Place the fresh leaves and any tender stems in a food processor and slowly drizzle oil as the processor is going until you have a thick paste. Then simply place them in an ice cube tray and freeze.
Once frozen pop them out of the tray and store them in a zip-lock bag or airtight container.
The other option is to place the paste in a zip-lock bag, press it flat and freeze. When needing to use it, simply break off the desired amount.
This will cost you a fraction of the money that you would have spent on supermarket pastes!