Bicycle Storage Rental near Center Park Slope?

Our craptastic landlord is making everyone move their bikes from the hallway but not providing any additional storage (there is tons available in the basement, they are just being difficult.) My husband found a place for us to store 3 bikes on 3rd Ave for $65/month, but that seems pretty heft given that we live 4 Avenue blocks away from there. Any ideas on where else we might be able to rent space to store our bikes? We would do outside, too, as they’re not particularly nice bikes.