Buying material and equipment with cash

[Umair Iqbal]

Hello fellow investors, i acquired a 4 plex a few months ago and just had my first tenant move on so i am currently working on getting the unit rent ready for next tenant. In the process of of renovations, i am finding myself shopping around for material and equipment such as appliances, doors and bathroom accessories.
In my quest of researching i am finding a lot of good deals on people either selling their used stuff at a very good price or people getting rid of brand new stuff that they never used due to not fitting or not liking the look.
My dilemma is that most of these things are paid by cash so how do you guys keep a track if you do the same and what records to keep so that if/when the audit comes up, i am able to show proof of it.

Thanks in advance