Rental in Singapore

To rent a room (or any other residential property), you need a proper residence visa. These are WP, S-Pass, EP, student pass, DP, LTVP (of min. 6 months duration), PR. It is not allowed to rent a place with a non-residential visa like SVP (tourist visa) or similar.
Furthermore, it is not allowed to rent residential property for less than 6 months.
These rules are by law (instated to cool the Singapore property market) and violations incur very high fines. DO NOT BREAK THEM!

Since you are coming for a shorter time and on a non-residential visa, your only legal options are hotels, hostels and serviced apartments. If you search a bit (and possibly negotiate) , you can probably find a place for S$2000/month or so. If you cannot afford that, don't come!

The minimum rental period for subletting a HDB is 6 months. However, URA has reduced to 3 months for private property including condos starting from May, 3017.
Details are below:

https://www.ura.gov.sg/uol/buy-property … ntial.aspx

Airbnb requesting govt to reduce it further, which is pending for future hearing.

For tight budget, you may try to see condos which are far from the commercial places, a common condo room can be rented with as low as $700.