Halloween fancy dress in Leeds?

I'm throwing a Halloween party this Thursday at my home and struggling to find somewhere in Leeds City centre (England) that sells Halloween costumes cheap but not too cheap (maybe around £15-£20). I need somewhere that sells costumes for both adults and children (my Son is 2 years old) but nothing too scary (my idea was black wings, like a fallen angel). Any ideas? I've tried culture vulture, next and new look but they don't sell what I'm looking for. Thanks in advance! And please, no ebay or amazon suggestions as I can't buy online atm, only in cash.