For a guitar and a provisional application with the drawings already prepared and in suitable form for filing and a good invention disclosure or prototype, I would estimate about 15-30 hours depending on skill level and the level of detail of your invention. The cost should be about the same as less skilled attorneys who take longer will typically charge lower rates that skilled attorneys. There are many variations in the methods attorneys use to write patent applications. Some are very cookie cutter and use very short background sections which reduces time. I tend toward that as litigation experience has convinced me the background is mostly used against you rather than for you. Some tend to just a best mode type disclosure with generalized broadening alternative language while others add many alternatives to attempt to enlarge scope. I tend toward the latter, which takes a bit longer. Some add claims to provisionals, while I tend to just do an omnibus claim, which shortens time considerably.
On a non-provisional you can expect to add 50% to 100% more time 18-60 hours, depending primarily on complexity and number and scope of claims. Since claims are what give coverage, you want time to be spent on them and to have them done well. Laymen rarely, if ever, write a decent claim. Even good patent attorneys often write poor claims. It takes years of experience or excellent training to write great patent claims.
Having said that, a great percentage of patent attorneys quote fixed prices for patent applications, usually giving the quote only after seeing the level of complexity and whether it is to be a provisional or non-provisional and an original app or a continuation or divisional.
For typical fees, there are a number of attorneys that list a schedule of MINIMUM charges online. Mine, which is low, but not the lowest (quality work seldom is), is now in its 20th year and 24th revision and is posted at www.burdlaw.com/usipfees.htm. It is widely used for purposes of comparison. If someone is much lower you should worry about quality. If someone is much higher, it likely means they are in a city and have higher overhead costs or that your case is abnormally complex.
Hope this helps. Call for free if you need more from any of the attorneys here. Billing discussions are almost always without charge with any attorney or firm and attorneys are seldom bashful about quoting fees and we all expect clients to ask, so don't ever be afraid to ask what things are costing. Attorneys want you to be happy and feel you are being fairly charged. Contrary to popular myth attorneys are the good guys and want to help you, especially patent attorneys.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
This depends upon the experience level of the attorney. I could likely write a patent application for a simple mechanical device in far less time than someone less experienced. You should instead ask how much such an application might cost. With more information, anyone on Avvo would likely be happy to provide a quote and/or a not-to-exceed price for their services.
This is not to be construed as legal advice, and I am not your attorney, A conflict check and engagement letter would necessarily be required before any retention or attorney/client privilege exists.
Whether it is a design patent or utility patent, it can be better to pay an attorney a fixed fee rather than an hourly fee. With the former, you do not have to be concerned about how many hours it should take or could have taken.
The answer provided is only for general information purposes and does not constitute legal advice.
Of course there are exceptions, but I find that most well-drafted patent applications take about 20-30 hours of attorney time. There are lots of variables in play, depending both on the complexity of the invention and how distinct the inventive aspects of your guitar are relative to prior guitars. You'll want to make sure your attorney takes the time to flesh out your invention, and describes more than one specific way to implement your idea. You'll also want your attorney to spend some time thinking about ways others might try to design around your invention, and build some protections into the patent application. A quick and dirty patent application that simply throws together a brief description of your invention can be cheap but of dubious value. That being said, most patent attorneys, after reviewing the invention and taking a look at the prior art, will give you a solid estimate, flat fee, and/or not-to-exceed price.
Of course there's more to it! Plus, we don't have an attorney-client relationship. This brief comment is for information only, and must not be relied upon as legal advice.
This is a very open ended question. But, many Registered Patent Attorneys, such as myself, will review your invention and give you a flat fee. Whoever you go to, make sure it is a Registered Patent Attorney. Not all attorneys are licensed to file patent applications. You should also ask for samples of their work.