These costumes are inherently expensive given the work that goes into them; I think that it will depend on your idea of 'low cost' - www.dancesport.co.uk have good costumes and sometimes 'preciously worn' items....
I do have a friend that makes these costumes for her daughter and others at the dance troupe, however for an adut latin maerican costume you can be looking at anything from £300 - £600 per piece!