So here are the most asked questions that I get every day!
These are generally between 800 and 1,500 yen (8-15 USD). Anybody could put these together - all the TV commercials show kids of about 10 (?) playing around with these kits. A whole leg for example may only be six pieces and because they are cheap, they lack detail and articulation. The HG series does have another audience however - the expert user who loves to modify these models so that they *are* detailed and *are* articulate - they carve off bits here and there and add extra joints and what have you. All HG models are snap fit so you dont need to worry about gluing your finger to your nose (for those who like to cleanse out your nostrils regularly). Judging form the pieces - you can probably put one together in less than an hour (without painting).
These are generally 2,500 - 5,000 yen. Models of late are particularly good because Bandai (after running out of Gundams to make) are releasing previously released MGs with new molds and frames - most are now so articulate that they can do the "adjusting-under-pants" pose. You can put together a MG model in an afternoon (without painting).
There are generally 10,000 - 20,000 yen. As the name of the series suggest - these "perfect" models have an extremely high degree of detail and articulation. The detail can be a bit tooooo much because you would spend half an hour on an engine or something only to find that it will be covered up by two more pieces - meaning that you would never see what you just spent half an hour on. Aile Striker has some nice inner engines but they are totally covered up - I never get to see them!
B-Club has a license to make Gundam kits but as they are not mainstream, the kits can be quite expensive - 17,000 yen (170 USD) for a 1/100 scale kit. As you can see from the link, all pieces are not colored at all - and to make matters worse - you still have to do a ton of mods to assemble - definetly not for the faint hearted.
All kits come with instructions and are in Lego style (dont need to be able to read Japanese). You can check out the Gundam modeling tutorial for more tips.
A macro shot of MG RX-78-2 Gundam Ver.ONE YEAR WAR 0079 (about 3000 yen-ish (30 USD.)