You don't pay the contractor for materials, but instead you pay the supply store for them.

Maybe have a thrift shop appraiser write up a valuation or something similar.If it is worth more than the threshold amount, you are required to store it for a period of time (you've done that already) and if the owner of the "stuff" doesn't reimburse you for your costs in that period of time you'll have to conduct a public auction. 

(plus no rent collection for that unit for half a year)He ended up abandoning literally everything he owned in the unit and the CA law states that I have to store that stuff for him for a period and then hold a public auction for all of it.

But that's not always, so don't assume it to be true.You can pick up a contract at a stationary store or a website like LegalZoom. 

I am curious if its better to have an open large building to store boats/ snowmobiles/cars etc and charge so much per linear foot or have individual units?

If you cannot get a clean feeling with fresh paint, caulk, faucets,  maybe a new in stock vanity top from a box store, you may need an overhaul.  

Go to Grocery Store hard to find Red Meat.

The house was not stored properly from the wholesaler/salesman and it is still in his name but he is trying to put some of the fault on me...In California I know you have to disclose any mold so we need to remediate it and have it signed off by an environmental mold test...Who is responsible for this nightmare.

Go into a store and walk out without paying, even though you could.

Like if someone needs a place to store their boat or RV.