Outside storage around here runs $40-60. No indoor (RV specific) storage available around here that I know of. We're out in the sticks though. My brother lives in the big city and stores his Kart trailer and a Miata inside a unit with a tall door (12wx14hx28l), for $155/mo.
2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)
Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!