I bought this 20 LED Dragonfly light set on eBay for about $5.50 with free delivery.
They run directly from the mains (240V), come with an Australian plug adapter, but have no approvals.
These lights should not be used in their original configuration.
My reason for buying them was purely to get the plastic dragonfly pieces to use with my own LEDs.
From the eBay listing I had assumed that they were just various coloured LEDs.
When I did plug them in, I saw that some of the LEDs are red/blue flashing types and the others are red/green.
This made made wonder if they could be modified to use on a low voltage DC power supply.
The diodes rectify the mains and provide approx 340V DC across the capacitor.
Each LED drops approx 2V (40V for 20 LEDs), so that leaves 300V to be dropped across the resistors.
Using Ohms law (I = V / R) , we can calculate that approx 8mA flows through the LEDs.
Be aware that the LEDs and all the wiring is at mains potential so exercise extreme caution.
You can use the second half (10 LEDs) of the above light set on a 30V DC supply.
All you need to do is add a resistor inline to limit the LED current.
With the 100R shown, the average current is approx 13mA.
My guess is that this current should be fine for the application.
Now, what to do with the other 10 LEDs?
With a little care, you can remove (bypass) the 4K3 resistors and add the 100R resistor as above to get your second set running.