Sin-Dps does not have much in the way of discounting if at all so your choices are SQ, GA or air asia and the published fares. It is about 600 GBP for a return business class ticket on SQ or considerably less in Y. It is entirely possible to avoid all contact with the boganesque as portrayed by Mr H, but it will cost you. I always use a concierge service to arrange my visa on arrival, allows you to sit in a lounge whilst bags, visas and customs are sorted.

You get what you pay for