Yup, if you can find a hotel (majority are sold out) you'll be paying through the nose unfortunately.
My advice would be to check out Air BnB or something like that...people rent out their houses/apts/rooms for a comparable price to hotels (especially if you have multiple people coming). Several of those still available.
Advise AGAINST staying in San Antonio and driving up. You'll be hating life. Traffic on 35 is already pretty terrible on a good day. On race weekend I predict it will be a nightmare and much longer than a 1.5 hr drive.
Going to be a fantastic weekend. SO pumped.