Why not start with me. I grew up in Singapore for 15 years and have been in touch with my friends and relatives over the years even though now I am living in the US.
You don't need 5 or 10 or 100 marketplaces to post to. You just need ONE good marketplace where everyone log on to. It's the 80/20 rule.
I have an account on this marketplace and I have 17 good feedback, 0 neutral and 0 bad feedbacks. More disclosure for customers.
My brother helps me meet the buyers and we talk about extending that service to you.
Post Ad on Singapore marketplace.
I will post your buy and sell item on Singapore's hottest marketplace and GUARANTEE enquiries.