Per incident means that the benefit amounts apply to each individual sickness or injury. Per policy coverage is usually offered by limited coverage plans.
Per policy period means that the benefit amount applies to any claims you make throughout the policy period. This option is usually offered by comprehensive coverage plan.
Though it may seem that limited plans cover more in this scenario, because of the way that limited and comprehensive plans work, comprehensive coverage plans actually protect you more in case of any claims made during the policy period.
Insurance rates are regulated by law. You can't find the same insurance plan for a lower price anywhere else