Like many, many other cooking items here, you may be out of luck!! I have found that I must scour the internet for substitutes to make myself. Since the main ingredient of custard powder is cornstarch, you may be able to easily make your own substitute by using the same amount of cornstarch with some vanilla flavoring in place of the custard powder. Livestrong has some good ideas: How To Replace Custard Powder | LIVESTRONG.COM
I purchased a 300g can of Lions custard powder at Hypermart about 6 months ago, I don't know if they are still carrying it. If you cant find I will give you my can I don't use it.
yes I have been using cornstarch with real eggs, but cant seen to get the right flavor maybe its the vanilla I need?
Yan Yan Marketing on Santa Rosa (I believe), has a pretty good assortment of baking supplies. Have you tried them?