Woolworths have recently brought out their own invisible zinc sunblock containing 20% zinc oxide. A 100gram tube costs around $10 and the consistency is lighter than the Cancer Council clear zinc. It's fairly easy to spread and I found it didn't make my skin slightly itchy like other zinc sunscreens. It doesn't leave a white cast on my light olive skin and I think it could be worn under foundation very easily.
However the two downfalls are that it blocks my pores and gives me sweat pimples, and that it is fairly hard to remove. I first tried removing it by massaging sorbolene into my skin for a minute and removing with a wet washcloth. Out of curiosity, I then massaged olive oil into my skin and removed that with a wet washcloth, and low and behold, all this zinc came off. No wonder zinc oxide sunblocks break me out. I will use up the rest of the sunblock on weekends but probably will not rebuy. I would suggest this would be best for people who don't get blocked pores.
EDIT - I have gone back to using this for several reasons. Firstly out of all the zinc oxide only sunscreens this is the most comfortable to wear. Secondly as long as I remove it using oil (I use almond oil) and then a foaming cleanser it doesn't break me out in pimples. Thirdly it wears well under makeup.