How much is taxi cab insurance in general for a used taxi?

Due to the many factors which are involved in calculating an accurate insurance quote, it would be advisable for you to call your auto insurance provider and ask them the question directly. There are too many variables involved for someone with a different age, different coverages, and whom resides in a different state to tell you. Each driver also has a different driving, claims, and credit history which could change their rates by thousands of dollars. When you call to get a quote, simply mention that you are planning to use a vehicle as a a taxi for business use. They will generate an accurate quote for you and your needs, based on all of the above plus any discounts you currently qualify for.

Amendment: The above is very true, but I can add this. I quote for taxi insurance in the UK, and I've just worked out that our mean quote recently is £1,243 (equiv to $1,717 (at 9 March 2009 rates)) but our median quote is £1,026 (equiv to $1,417 (at 9 March 2009 rates)). Median means take all the figures, put them in order and choose the middle one. What that shows is there were two or three high quotes there, clearly high risk cases, that raise the average. So the answer is, in the UK at least, around a thousand pounds a year.