How much does it cost to file and obtain a patent? Who pays the patent costs? What is the price range for a professionally written patent.
This is a pretty broad question, so I fear my answer is going to be reasonably broad and vague in response.
How much does it cost to file and obtain a patent?
At the USPTO, the basic filing fee is USD 280, with discounts for small and micro entities. This doesn't include attorney costs for filling and drafting, or for the costs that arise from prosecution.
The cost to obtain a patent is impossible to give. It could be a few thousand or it could be ten times that. It all depends what happens during prosecution.
Who pays the patent costs?
Whoever wants the patent, ultimately.
What is the price range for a professionally written patent?
This is impossible to answer with any accuracy. It depends on the attorney and the nature of the invention. It could be USD 1000 for something very simple. It could be USD 30,000 for something extremely complex.