i take sports photos and sell photos to the kids and parents all the time. there is a way to do it, but i have to tell, it isn't as straight forward as you think. singapore and oz are two very very different markets. the standard way of selling prints online will not work the way it does in other countries and if you don't know how to market yourself and do not understand sports marketing i suggest you don't even attempt to try it the "oz" way.
you have to consider this point, and it is a huge point. in oz, you might have one or two photogs for miles around. in singapore, there are hundreds on every block and photogs are a dime a dozen. this is where you need to understand sports marketing and branding because that will separate you, it's worked heaps for me.
here's the thing. when you open yourself up to this style of doing work, events organizers will also come to their sense and say hey, i will hire a photog, not pay him, and he can earn from photo sales. you are walking a fine line and frankly speaking, the way the market is here, if you do this and do it wrong, you pulled the plug for a lot of event shooter. i suggest you think long and hard because again, singapore market is not oz market.