Setting up a SEP or SIMPLE IRA is a snap; you only need to fill out a few forms. The plans are available through most brokerage firms, mutual fund companies and banks.
Individual 401(k)s are a little more complicated to set up and expensive to administer., You’ll need to find a plan administrator, and unlike corporate 401(k)s, which often offer dozens of funds from multiple fund families, many solo 401(k) providers restrict you to one fund group. You’ll find the widest range of investment choices at fund “supermarkets” like Schwab. Fees vary widely among 401(k) providers, but almost all have set-up charges and annual fees. Many firms will waive some expenses for larger accounts. You can search for a provider at 401khelpcenter.com or ask your accountant or financial adviser for plan recommendations.