If buying a children's bike, unless they want to be a downhill racer, it doesn't have to have suspension. All that does is add weight. Often childrens' bikes, especially those bought from toy shops or on the internet, end up being heavier than adult's bike, due to cheap, poor quality heavy steel being used, as well as having poor quality components.
Sometimes, like the bike shown in the photo opposite, they're not even built correctly, as the forks have been put on the wrong way round, as the brakes should be at the front, and the steering tube is extended way beyond the maximum safe limit.
Therefore avoid what looks like a bargain, as your child will end up with a bike that's hard to ride and is likely to break down, or worse, could cause injury.