The costs of all the tests and reports required is where the expenses can really start to add up, depending on your condition. I think in your case the mental condition will be the most cumbersome to overcome.
I did a initial Special Issuance and subsequent applications by myself without any major issues. It did cost me several thousand dollars for the specialist visits, tests and reports that were required. Many of these tests are required every year or two depending on the conditions of your special issuance. Insurance does not pay for most of them.
In the end you have to decide if it's worth it. My FAA medicals are no longer $100-150 every six months.