If you are the sole owner (or just you and your spouse) and expect to be that way for a few years, consider the benefits of an individual 401(k). The contribution limits are higher than an IRA, and there are usually no fees involved. You can google "Individual 401k" and any of the major investment firms (Fidelity, Schwab, etc) will set one up free of charge. This option gives you a lot of freedom to decide how much money to put away without any plan management fees. The IRS site has all the details in an article titled One-Participant 401(k) Plans.
Once you have employees, if you want to set up a retirement plan for them, you'll need to switch to a traditional, employer-sponsored 401k, which will involve some fees on your part. I seem to recall $2k/yr in fees when I had a sponsored 401(k) for my company, and I'm sure this varies widely.
If you have employees and don't feel a need to have a company-wide retirement plan, you can set up your own personal IRA and simply not offer a company plan to your employees. The IRA contribution limits are lower than an individual 401(k), but setting it up is easy and fee-free.
So basically, if you want to spend $0 on plan management fees, get an individual 401(k) if you are self-employed, or an IRA for yourself if you have employees.