The Landlord keys are specialty made so no duplicates can be made and the cartridge swapout is pretty cheap (~$13 to replace).

A Delta cartridge is in the $40-50 range.

You may need to remove the faucet cartridge. 

Poorly sized or clogged or malfunctioning filter cartridges, water softener or iron filters etc.Check and change filter cartridges and inspect your backwashing filters and water softeners if you have them.

I don't know if you make money off mold remediation and magic special cleaning solution and negative pressure devices and expensive pink-colored P100 respirator cartridges and how awful bleach is and the whole rest of the mold remediation con.

Including-Dues-Business cards-Post cards-Signage-Postage-Handouts-Printer cartridges and printer (I know most offices have them but being able to print at 2:30 AM while wearing slippers is pure value)-Paper-Open house signs-Open house refreshments, booties to cover shoes, bucket for water bottles, coffee maker, coffee, cups, sugar etc. and picture frames for "Please remove shoes signs" etc-Desk fees (which will very and so will your split)I would honestly say about $5,000 as a guesstimate to get really rolling.

What the EPA recommends for asbestos-remediation work and what I do is wear a half-mask respirator (I really like mine, a 3M 7500-series http://a.co/jkTKaZG) with P100 pink-colored cartridges.

If it is a dripping faucet, I would try to replace the cartridges first.

The other really nice thing about it is that the remanufactured ink cartridges on eBay are like 1 buck or 2 a piece.  

While doing the pre purchase walk some plastic cartridges were found in the cabinets.