Another good choice for a 12 year old is the Orion Starblast 6 for $379. If the budget stretches to $579 the Orion Starblast 6i Intelliscope, would be a better choice. They are both the same basic 6"/F5 Tabletop dobs. The 6i model has the same "push to" Intelliscope Computer the larger scopes have, but in a more compact package. They both have a parabolic mirror, which is important.
Here they are advertised on the Bintel website.
Both these scopes are the same except for the push to computer object locator. They should have the capability to run to between 250X and 300X on the moon and planets which is ideal for those targets. They have a decent aperture of 6", so they can bring in quite a few of the brighter DSO's and do a decent job on them as well as the moon and planets, yet still very small and light being a table top scope and only about 75cm long.
Whilst these scopes don't have quite the same optical performance as an 8" dob, they are a lot smaller and more portable to store and handle for a 12 year old. They will outperform a 4" achromatic refactor on all types of targets.
If you wished to go with a small refractor so that it could double as a terrestrial scope, I would recommend the
Meade Star Navigator 102 which has a focal ratio of F7.7 and the capability to run to over 150X on the moon and planets, but is restricted by its smaller aperture and is limited in its ability to view Deep Sky Targets
Another reasonable choice would be this 90mm/F10 refractor advertised on the Ozscopes website. This is similar to the 4" Meade in that it will go to 150X on the moon and planets, but is restricted by its smaller aperture and is limited in its ability to view Deep Sky Targets.
If you wanted a telescope that was very good as a telescope for viewing terrestrial targets due to its portability, with a limited capability as an astronomical telescope, due to its inability to go much past 100X on the basis that is a 4"/F5 achromat and also limited in its ability to view DSO's due to its small 4" aperture, then the
SW102 would be a good choice. As mentioned in the description on the Bintel website, this telescope is proposed predominantly as a Terrestrial based telescope, with the capability to do some astronomy; and IMO this is pretty accurate description of its capabilities.
Cheers,
John B