My husband and I stayed at the Cedars on the Brazos in Glen Rose, TX. It was absolutely wonderful and I believe it's in your price range. I would go back in a heartbeat!
Although it's about a 2 hour drive, I highly recommend Salado, TX. The Rose Mansion is wonderful and they have cute little cabins, too. Very nice place.
Jefferson, TX has some nice places, too. I can't remember the name of the one we stayed at. I want to say it was the something Colonel's House and one of the bedrooms was supposedly haunted. All of the rooms are named after poets. It was a gorgeous place and I would go back again!
Go to bedandbreakfasts.com for more info. Good luck! B. - Arlington, TX