If you're willing to do a lot of studying and to take the risk that something might go wrong in ways you cannot anticipate, then the answer is YES.

It is possible to learn how to search for "prior art" and to generate a patent application for a new gizmo by reading David Pressman's excellent book Patent It Yourself published by Nolo Press, www.nolo.com. A provisional U.S. patent application can be filed by an individual inventor as a "small entity" for a government fee of less than $125.00.

Unfortunately for an individual inventor, patents are very expensive to obtain (actually, when the multi-year process is done, it may cost maybe 10x what you suggested above). The cost of obtaining a patent is about the same if it is for an individual inventor or for a multi-billion dollar company; there are no economies of scale. The preparation is expensive, as is the subsequent back and forth negotiating (called patent prosecution) with the US Patent Office.

But here is what you can do to keep the costs down:

(1) Get a copy of David Pressman's book as Gerry Elman suggested.

(2) Go talk to a patent attorney in the field that you are considering getting the patent. Make sure that you not only can explain the technology, but you need to explain to the attorney how you plan on making money off the patent, so that the attorney is focused on getting you the patent that is going to be valuable to you. Unless you sign an agreement for him/her to represent you, you wont have to pay a cent.

(3) Technically, you can obtain a patent yourself, but the reality is, that if you want a good patent, then you will need to engage a patent attorney.

(4) If you are interested in talking to a company who might want to use in your invention and you are worried about the company stealing your invention, then you don't actually have to obtain a patent, but simply filing a patent application may be sufficient. If the company and you can agree that your invention is valuable to them, then later you continue in the prosecution of the patent application to obtain a patent. If on the other hand the company is not interested in your invention, then you can simply abandon the patent application to save on future costs.

(5) You should be able to save money by doing a lot of the writing of a patent application yourself, with the attorney re-writing it instead of the attorney writing the application from scratch. Patents are not copyrighted, so feel free to copy from other patents, but make sure that you give a complete list of patents that you've used to your patent attorney.

(6) Ask your attorney about the possibility of filing a provisional patent application. It is cheap in the short run, and may be helpful for your situation.