What is the cheapest form of child care?

The cheapest form of child care is the one you don't have to pay for. Two really great options are to either have friends or relatives watch your kids or look at a childcare co-op. Both have their pros and cons, but you probably won't find a cheaper child care option as far as costs go.

Is it better to have a nanny or daycare?

If your family has a lot of disposable income and you want your kid to have more individualized care, then a nanny is a good option. If cost is a factor for you, or you want your kid around a more diverse group of kids, daycare is a good option.