I have one of these: http://www.diy.com/nav/fix/tool-stor...skuId=11758488

Although mine is B&Q's own brand and was about £25 at the time. Have to say, I love it. Yeah it's quite big but it does mean there is plenty of room for things and having the wheels is a big advantage. It's got a couple of ledges that act as handles at the sides, which make it quite easy for lifting in and out of the car and, most importantly, it makes an excellent seat.