It's better to get a full-tank of gas than making multiple trips to the gas station. While you may need to pony up more money for gas when you fill up, you'll save money in the long-run because you'll make fewer trips to the gas station.
Bottled water is bad for the environment, so consider a reusable metal bottle from SIGG (www.mysigg.com). These bottles come in a variety of colors and patterns and will save you from having to buy bottled water every week! Instead of using those flimsy plastic cups, you can bring your SIGG to the office and fill 'er up using the water cooler.
Tip: You can flavor tasteless water with slivers of cucumber (for spa water) or with an Emergen-C vitamin packet powder for a boost of B and C vitamins and immune-boosting zinc.
Ditch plastic plants for the real thing. A few houseplants -- like ivy and even cacti -- will help naturally filter the air in your home by absorbing bad gases like formaldehyde and benzene all while absorbing CO2 and giving back oxygen. Ask your local nursery for drought-resistant plants if you have more of a brown thumb with live plants or look for beneficial plants such as aloe vera, which can have medicinal properties, too.