Yes, my mouth fell open too.
However, let me say, that I think it is worth it. While you are not allowed to enter any of the buildings (what are we, peasants??) you have full access to the grounds for hiking. This is certainly cheaper than paying for a $450/night hotel room or a $60 lunch, which are the other two ways to get onto the property. When I arrived, I had to park at the bottom of the mountain then had the option of taking a shuttle 1.5 miles up to the main hotel or hiking up. I decided to take the shuttle up and hike back to my car later.
Main Hotel on Mohonk Lake
There are many trails on the property, most of them being old, flat carriage roads. Most of the trails begin at the main hotel. I had read about a 45 minute rock scramble on the property called the Labyrinth that will eventually take you to Sky Top which is the highest point at Mohonk. I was excited to attempt this, but because it had been raining and I wasn't wearing the proper shoes, I had to abandon this plan after 5 minutes and a near fall.
I decided to hike up the semi-steep path to Sky Top where there is also an observation tower. The views it supplies are incredible and allows you to see into 6 different states.
I headed back down to hike the flat trail around the lake then headed back down to my car. None of the trails at Mohonk are remotely difficult, except for the rock scrambles. Overall, I'd say the views alone are worth the $25 entrance fee and I will probably return when I go up there next year.