Building and renting basement storage units?

[Erin O'Connor Smith]

Thinking about building secure storage units in the basement of a 4plex. Any experience with the best way to build for the most value?

Also, how to price them for the tenants of these very simple 1 bed/1bath apartments that currently rent for $500-550 each per month. Include in rent (and increase slightly) or offer as a separate amenity? And for how much each?

Thanks!

Erin