Look in the cruisers/lowrider websites...
Here is one but it is ~$200 which seems to be the low average price. Here is
another one but doesn't seem as complete. Best bet would be to find a used trike somewhere or buy a new one. WM is selling a complete
Chinese Schwinn Trike for $250. Might be the best way to go if someone will go over it with a fine tooth comb for him.
Aaron