After eyeing the pricey Ubiquiti 10G adapter, I spotted the Orico Thunderbolt 10GbE Network Adapter that the Singtel technician used during my 10Gbps setup. At S$147 after vouchers, it is around 50% cheaper than the Ubiquiti option.
Hunting for a USB-C Ethernet adapter, I found Belkin's at S$49 overpriced versus Anker's at S$32. For a little more, the Anker USB-C to 3-Port USB 3.0 Hub with Ethernet Adapter adds extra USB ports, so I chose it.
I ordered the Apple Thunderbolt to Gigabit Ethernet Adapter for S$38 on the very day it was announced at WWDC 2012, and it arrived the next day, so Apple has ready stock in Singapore. Funan's Multimedia Integrated didn't have it.
I got the Apple USB Ethernet Adapter for S$35.51, down from S$38, at iStudio in Changi Airport Terminal 3 on my way to Malaysia for my birthday. Since the MacBook Air has no Ethernet port for the sake of slimness.