What age bonsai should I buy? What type of tree is good for beginners? If I try to start from seed, will I be too old before my tree actually looks well styled?

You are basically after a manual here.. These are not simple quick answer questions.

Regarding selecting raw stock for bonsai, I wrote a little guideline how I think one should go about selecting: www.growingbonsai.net/growing-bonsai-you...ry-stock-for-bonsai/

Wat type of tree is good for beginners.. Depends on where you live. In the tropics a larch would be no good. And in norway a ficus is not ideal.

In general juniper, maples, larch, ligustrum, elms are good species that take a lot of abuse if growin in their natural climatic regions.

From seed to a decent small bonsai is a 15-20 year process most of the time (Although I have made mame sized bonsai in 4 years from berry seedlings). If you o the seed route, ALSO buy some plants. Growing from seed is mainly that. Growing. (Some background info: www.growingbonsai.net/growing/propagation/ )

Currently in California, and I could be moving to Florida.

I would say you are in a region where ficus and bougainville are interesting bonsai species. And if you are lucky you might be able to get Brazilian raintree, the one species I am trying to find for growing at home, semi-indoors (They can only stay outdoors for 4-6 months in my climate)..

Thank you!

Do you think that I could do an root-over-rock bonsai?

leatherback wrote: And if you are lucky you might be able to get Brazilian raintree, the one species I am trying to find for growing at home, semi-indoors .

Ok, ok, I know I owe you that, Leatherback .
Believe me, I'm working on that. All 50 seeds I had did NOT sprout, and it seems I can not get a reliable source of good seeds of BRT.
IF it serves as consolation, I am right here in Brazil and...
Still looking for one to buy..

It was NOT a jab at you!

This year we will meet up. Maybe during my trip to brazil in late May I have some time to see you in Sampa.