Answer Base

It seems to be cheaper to go the gumtree or trade-it route. but is it wise to buy a car this way? my budget is about £3000 for somehting small and reliable.

You can always try ebay i have bought and sold many a car via this method, but if you do consider buying a car from ebay make sure you know what your buying...look at it first and do all the usual checks like hpi etc.. nice luck : )