If you are just one night, bite the bullet and take hotel from the airport. Yotel is cheaper than Crowne Plaza and its still easily accessible from the terminal. Im also assuming you are taking the morning Scoot flight to MDC.
Going to the city might save you close to a 100$ in hotel price, but you need to spend close to that in taxi's ect.
One option could be leaving luggage at the airport (even better if its checked through to MDC), it costs under 20SGD per item. Then just take MRT with HBO (i wouldnt go with alot of luggage) to somewhere like Aljunied station (before the city coming from airport) for semi-decent hotel for the night. And not too far away to catch the moning flight.