Runners registering for the 38th Grandma's Marathon have through Friday to enter the race before the price increases. On Saturday, the current entry fee of $90 goes up to $95 for two months. After April 1, the fee increases again to $110. Visit grandmasmarathon.com to register for the Two Harbors-to-Duluth race on June 21. The marathon field is limited to the first 10,000 participants.