Whats the best way (cheapest and convenient) to Reach Dum Dum airport from Howrah.

EDIT: Howrah Railway Station to Airport

Most of time, I face network issues outside railway station to book any cabs. And had to book an expense cab (600-800). Are there any bus service for Airport directly ? If yes, from where to get them ? Also, if booking cabs which one to go for( cheapest) for the same ?