The minimums may vary from company to company, in a specic fund program I use often, there is no minimum if the investor sets up a systematic investment plan. 529 plans come in a few diggerent shapes. The Illinois version is a pre-paid tuition program where investors csn buy semesters of school ahead of time. The price of the credits will be based on the age of the child, the younger the child the cheaper the credits. Illinois investors can choose between this program and the 529 mutual fund programs available.
Many investors choose to participate in both.
In the prepaid tuition program the money is typically invested in bonds, where the mutual fund alternatives are often more stock heavy. The mutual fund companies typically offer a few fund choices, with varying degrees of risk. The better 529 plans in my opinion offer both choices. The money in a 529 plan grows tax deferred, much like a 401k account. Preferably the investor will not withdraw funds in a 529 plan until they need the money for higher education expenses.