In my experience - if you just use Toyota stuff - you generally don't get leaks - my car is on 219,000 and it's all original - water pump , matrix , radiator.
From other Toyotas I've had - I've often found that the water pump and or rad often started leaking after putting non-genuine coolant in. I have also found that on the majority of customers cars that I change rads / water pumps on the stuff that's in there isn't genuine Toyota.
It's £16 more than other stuff - ready mixed so you get the concentration correct - that's around 2 days petrol for most people - it doesn't need changing that often so spend a little more and hopefully it will save you more.
It's been debated a few times