https://www.irs.gov/retirement-plans/plan-participant-employ...
You will need an attorney/accountant/actuary to make sure your S-corporation is valid and does not ever create some situation where you lose that status. Then you need a good accountant that knows the ins and outs of keeping track of your S-corporation accounting especially two corporate-level attributes—earnings and profits (E&P) and the accumulated adjustments account (AAA).
Then you will need an actuary. Most actuaries have transparent pricing like the following:
http://pensionspecialist.net/defined-benefit-plans/
The goal for a single owner S-corp will be to maximize your salary to defer as much as possible. The money put into your defined benefit plan is tax deductible. The contribution limits are high and are set with your actuary.
Your goal will be fund your benefit plan up to 2.5 Million. When your retire (early at 55 is possible I think), you can take the lump sum or an annuity. At this point you pay taxes on it.
Meanwhile, you can manage and invest your fund according to what you and the actuary think is best. The investments/contributions/plan will change due to various factors.
I believe when you hit 2.5 Million you are fully funded. You can freeze your plan at that point or continue funding it. Ask an actuary.
This is what doctors, attorneys, and high earning consultants do. Very few corporations provide this any more.
If you want to look at examples, put your zip code into this page: http://search.pbgc.gov/search/InsuredPlans/InsuredPlans?quer...
The added benefit is that your pension is insured by the government via the PBGC. For small firms the insurance rates are affordable.
http://www.pbgc.gov/prac/prem/premium-rates.html
Here is a sample of deductions per plan. It seems dated, these amounts should be more by now.