This seems to be the cheapest place to get it before and even after using the vouchers... Even the Mathmos's own website sell it for £28.99 compared to £14.90 from here! Don't forget that these use LED lights and so should not be expensive to run....
"Mathmos is back with another fantastic piece of glowing art for your home! The Mathmos Poplight is a colour changing lamp with a difference. A mouth blown glass cover encloses a colour changing light which is created by chip controlled LED's. Watch the beautiful glow transform from red to blue and back again! Simply push down on the top of the Poplight to switch it on and off."
This Mathmos light phases from red to blue and is switched on and off by pushing on the top!
The Mathmos Poplight is made from mouth blown glass and mirrored plastic
Our colour changing light works through an A/C adapter (included), not batteries
The Mathmos lamp measures approx 16 cm x 12 cm x 12 cm
This Poplight makes the perfect gift for ages 12 to 120!
Create ambient, soothing lighting in your home or office with the Mathmos Poplight. This fantastic lamp will soothe, relax and make you feel all lovely and gooey inside as it changes slowly from sensual red, to hypnotic purple, to calming blue. Create lighting effects at parties, dinners or cozy nights in with the Mathmos Poplight.
Also checkout the Mathmos Thaw:http://www.find-me-a-gift.co.uk/mathmos-thaw-ice-tealight.html
And Mathmos Space Projectorhttp://www.find-me-a-gift.co.uk/gifts-for-men/unusual-gadgets/mathmos-space-projector.html