Hi,
there just had a sale last weekend. we got our Queen Size Heritage mattress at $1599, $300 off. Paid deposit of $400, due for delivery in Dec 2009.
The salesperson told us that they will increase the price by about $600 even though it is the GSS. I think your best bet will be to go to the Simmons shop at the International Furniture Centre at Sungei Kadut Loop and ask them for last weekend's price.
Don't worry about the price going up again because they have a price guarantee and they promise to refund you the difference in cash if they lower the price or if you can find any shops selling the same mattress at a lower price before your delivery is due.
You can speak to Ace, the salesgirl who attended to us. Very nice Malaysian girl.
Good luck! Oh and King Koil having 50% off, you can consider them too, they are n the same building.