Actually Costco sells them in a three pound bag ($14.99) .... that should last at least a week. They sell a three pound bag with pepper for $16.99.
Some things to remember:
1. Ingest the nut and do not use it as a muse.
2. Remove the shell before ingesting.
3. Pistachios work best if ingested with beer (.... thats ingested not injected).
4. At only 140 calories an ounce you can supply your body with its daily calorie requirement with only two handfuls (0ne and a half handfuls if you also ingest a beer).
5. By eating pistachios you are supporting the California pistachio industry and keeping hundreds of California nut-stuffers employed (they're the folks who package the nuts in the handy little shells).