Check out Vonlane. They are deluxe buses that cover the Texas triangle. We use them for work to move our guys between Houston / Austin regularly and people seem to love it. It's pretty cheap, comfortable, and has wifi.
Will second (third?) Vonlane. After using them, I don't understand why anyone would prefer a flight between Austin and Houston compared to Vonlane. The time is about the same when you factor in the hassle of airport security, and Vonlane goes downtown-to-downtown. The bus is super comfortable with big seats (comparable to domestic first class on an airline) and the service when I've gone has been fantastic. I can also get a ton of work done on the trip if so desired. Once I went and there was an accident on the route that made the trip from Austin to Houston about 45 mins longer, but I didn't care at all as the bus was so nice to work in.
They're priced that way because they compete with shuttle flights, and most importantly, they are far from a normal "bus" experience - the images shown at https://vonlane.com/ are accurate IMO.
