Every late August and September, one of our local vegetable stores sells huge bunches of basil. This year each bunch cost $1.50. There are one and a half bunches in the vase (the other half bunch is hanging to dry.)
Mixed with olive oil, garlic, pepper and a little seasalt, it reduces dramatically in the food processor.
I put the pesto into icecube trays. Note that there is no cheese or nuts in the freezer portions. We add those when we use the pesto to make the finished dish. (Take a look at an pasta tossed in basil pesto with whole toasted pinenuts.)
The trays are double-bagged, with as much air sucked out as possible, and put in the freezer.