I only know about a couple of ramp's fees : Herington Marina ramp - $20 Chimney Rock ramp - $15 .... but I'm sure most of the others are much the same. And yes, you are correct that it is "expensive" and not all ramps are in the "best condition". Considering the current level of 725.8 .... I'd be calling to see if it's even possible to launch/retrieve a boat at this time. 725 is supposedly Winter Pool, but I have seen Chimney Rock ramp have a wooden platform attached to the end of the ramp to facilitate launching ... because the ramp ends on a cliff drop.
On another note ... Chimney Rock Marina's website says they're "Closed for the Season". Not sure if that means launching is free, or even if launching is even possible.