$35 for them to carry your tanks to the boat for you?!? I can't think of a single boat I've been on where they didn't schlep rental tanks for you automatically. Some of them even ask to schlep your gear bag for you, too. $35 is outrageous!
The fee is to get rental tanks (or other gear) from the shop to the boat. Given they're an hour apart and I live an hour from the shop, that's a big convenience for me.