I have to agree with Allan here go for the slightly dearer Heritage 130p. I have one and it's an excellent little scope and will be so much better than the others you have mentioned with its larger aperture. Many would normally say go for bigger aperture than that and I would normally agree. But this would be ideal for a 4yr old as it's shorter than bigger aperture scopes and is incredibly lightweight and easy to use.
There is one available here in the classifieds going for $150.
http://www.iceinspace.com.au/forum/s...d.php?t=124655