sir once this situation arrived with me also ...i deboard at delhi cantt by mandore exp then i went to palam (as mandore does not halts at palam) by delhi rewari shuttle which arrived just 15 mins when i deboard at delhi cannt and from palam station i hired a local taxi for airport...but the taxiwala suggested me that i should hire the taxi from delhi cantt only which is more convenient to go for airport....now u can decide ahich way you want to go...