tigershark,
yes, seletar do sell softies.. but u need to find out when the shipment is.. the last time i went down, on friday or thursday, hardly any corals left..
to get there,
take 86 from ang mo kio, alight at the halfway house (gracehaven i think) and walked towards your right (facing the halfway house) after alighting, see the road sign; seletar farmway 1; turn in.. and walk all the way.. u should pass a junction with a building with a seahorse logo.. continue the journey till u see a signboard saying: marine fishes and corals, on your left.. the place should be 95 seletar farmway 1