The cost of a storage unit monthly depends on the size of the public storage unit you want to rent.
The smaller the size the less the cost and the bigger the storage unit the more the monthly cost.
I used to rent a 5 X 5 foot storage unit and it costed me $50.00 per month.
A 10 X 15 foot unit can cost from $75.00 to $150.00 per month and if you want a climate controlled storage unit the cost will be even higher.
Climate Controlled storage units can cost as high as $150.00 to $200.00 per month depending on the size of the storage unit.