There are lots of seasoned growers here, the worth of a tree is variable. I would suggest you get some garden center material and learn how to keep them alive with proper watering and nutrition then practice techniques like pruning and wiring. That way if you kill a $10 - $20 tree its no real loss. Think how depressing it would be to drop $100 - $200 on some good quality pre-bonsai and kill it learning, or even worse to dole out $500 + on a nice finished Bonsai and water it to death. The real value of tree is what you feel its worth and what you can afford, what may be a steal to one guy for $1000 could be only a dream for another.
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