I'm building a set of planters, and originally I was planning to use succulents; unfortunately, succulents are not too keen on growing vertically, so I'm contemplating going with bonsai trees. My exposure is limited to a few trips to the botanical gardens in Kyoto, and then the Denver botanical gardens, ( winter & summer if people want to see the Kyoto pictures)
They will end up living in a 2" by 2" and 2" deep planter for hopefully a very long time, no direct sunlight but plenty of ambient light. I can add artificial sun light if needed.

I'm looking for some breeds to look into, and where I could buy cuttings to start from?

To be honest you are not going to get a very good response (or even a nice one). If you are putting bonsai in a planter then it is no longer truly a bonsai. With some exceptions (rock plantings) bonsai definition is "tray planting". To add to that a plant is not a bonsai until it has had several years of training. Even the famous bonsai of today are not done training. Another misconception is that bonsai can grow indoors and while some species can this is not the case for most. Most common species used for bonsai will need full sun or part shade but 100% outdoors. I hope this helps in your decision.

ah thanks, is there a better word for trained miniature shallow planting?

BasHamer wrote: ah thanks, is there a better word for trained miniature shallow planting?

There's no better word for it, unless when you're referring to bonsai, which are trained miniature trees in shallow pots, which your plants are not.