+1 to what EvilV is saying; Raleigh also sell a rebranded version of Dahon's Boardwalk model for a bit less than the Dahon equivalent that might be worth looking out:
http://www.raleigh.co.uk/bikerange.aspx?rangeid=9
Best to stay clear of some of the other 'new' folding bikes on ebay - they're not really up to sustained use but by this I'm not bracketing Downtube which by the enthusiasm on this site are definitely an excellent budget option