Great points brought up here
I want to emphasize, the things I keep are known fast movers or things that repeatedly caught me off guard or allowed a fast sale/repair like Idler and tensioner pulleys
I did not go crazy with my purchase but was able to buy about 3500 of parts which were 45% below cost, they just wanted to pay off what they owed.
I went through from memory and bought the following
Brake Pads
Belts: (Based on customers vehicles)
Hoses: (based on customers vehicles)
Pulleys
Tensioners
entire light bulb stock
brake line fittings and adapters
Edelman fitting cabinets and fittings
Spark Plugs again based on the Vehicles I see and know are coming up
Throttle body gaskets for the common vehicles that require cleaning
Relays
Fuses
I also keep a full stock line of
Oil Filters with bulk packs I have over 250 filters
Brake Pads
Brake hardware for pads that I move a lot
I have Some: Wheel cylinders, rad caps, seals, brake hoses etc that I have accumulated along the way.
A lot of guys will chime in and say this may be crazy, but if I have a walk in customer that needs an oil filter and I have to wait or send someone out there goes my profit.
I also take advantage of my NAPA GOLD filter sales, some of prices are unbeatable and allow me for that extra margin of profit.
That being said, my main parts room is running out of space so I have expanded it to another section of the building and at Times I forget all what I have.
The other side of the software that I like is the fact I can track things, and I know on some it shows a profit margin as well.
I keep Drums of 5w20, 5w30 on stock as well as quarts of others, 10w30, 10w40, synthetics, 15W40 Antifreeze etc etc.
I have a pretty organized system for the filters and pads but