I contacted Spaceport about the February event and here was the reply:
Hi, John.
Thank you for your interest.
The event is open to all vehicles. It is invitation-only and is exclusively for 200+mph vehicles. The field is limited to 30 teams and the entry fee is $3000.
Please feel free to contact Steve at 812-305-0710 to discuss further details.
Best Regards,
CJ
Maybe, over time and a larger entry field, cost will come down.