Hi, I was in Tesco's Gorton Manchester and they have the 120 W Ring E can for £12 which i currently the best price I can find.
It is a nice quality item, I think the outside i made of aluminium which is a nice touch. It is can shaped and can therefore fit in cup holders in you car. it is the 120W model that doesnt have a USB port. (that is the 150W model) but im sure 120W is more than enough for most peoples needs.
I bought it to charge/power my netbook when im out. And I think most laptops would also be fine, even some small portable tvs would be fine im sure. And mobile phones, psps NDS etc will all be fine. So yes its a nic piece of kit indeed and is a very good price as on tesco site it is £35.00. Instore only im afriad, i imagine it isnt store specific but I reckon only decent sized Tescos will stock such an item