Hi,
You can try posting it at www.nationproperty.sg
It is linked from HDB website (www.hdb.gov.sg). Hence when people looking for HDB transacted prices, there is a link for users to search for property for sales, and this link go to nationproperty.sg
But do take note that when you post your listing there, do not put in the actual unit number (unless you want people to know)
It is not easy to sell it by yourself if you do not have useful tools. And, you also need to read through HDB website on the rules and regulations and what to look out for.
Another thing is when you advertise your property for sale, it is better to get a temporary lines for your mobile as well as email. so that after the property is sold, you can cancel the temp lines and accounts. You will be surprised by how many nuisance calls and spam emails you will be receiving.
Be prepared that by posting your listings on website, the response may not be immediate. You should also try newspaper advertisement.
All the best.
Serene
www.tgpagar.tel
www.twitter.com/tgpagar